developmental source hypothesis

Chapter 2: Developmental Theories

Learning Objectives

At the end of this chapter, you will be able to do the following:

• Define theory
• Describe Freud’s theory of psychosexual development
• Identify the parts of the self in Freud’s model
• List five defense mechanisms
• Describe five defense mechanisms
• Appraise the strengths and weaknesses of Freud’s theory
• List Erikson’s eight stages of psychosocial development
• Apply Erikson’s stages to examples of people in various stages of the lifespan
• Appraise the strengths and weaknesses of Erikson’s theory of psychosocial development
• Compare and contrast Freud’s and Erikson’s theories of human development
• Describe the principles of classical conditioning
• Identify unconditioned stimulus, conditioned stimulus, unconditioned response, and conditioned response in classical conditioning
• Describe the principles of operant conditioning
• Identify positive and negative reinforcement and primary and secondary reinforcement
• Contrast reinforcement and punishment
• Contrast classical and operant conditioning and the kinds of behaviors learned in each
• Describe social learning theory
• Describe Piaget’s theory of cognitive development
• Define schema, assimilation, accommodation, and cognitive equilibrium
• List Piaget’s stages of cognitive development
• Describe Piaget’s stages of cognitive development
• Critique Piaget’s theory of cognitive development
• Describe Vygotsky’s sociocultural theory of cognitive development
• Explain what is meant by the zone of proximal development
• Explain guided participation
• Describe scaffolding
• Compare Piaget’s and Vygotsky’s models of cognitive development
• Describe Bronfenbrenner’s ecological systems model

What Is a Theory?

Students sometimes feel intimidated by theory; even the phrase, “Now we are going to look at some theories…” is met with blank stares and other indications that the audience is now lost. But theories are valuable tools for understanding human behavior; they are proposed explanations for the “hows” and “whys” of development. Have you ever wondered, “Why is my 3-year-old so inquisitive?” or “Why do their classmates reject some fifth graders?” Theories can help explain these and other occurrences. Developmental theories explain how we develop, why we change over time, and the influences that impact development.

A theory guides and helps us interpret research findings as well. It gives the researcher a blueprint or model to help piece together various studies. Theories are guidelines, like directions with an appliance or other object requiring assembly. The instructions can help one piece together smaller parts more quickly than if trial and error are used.

Theories can be developed using induction in which several single cases are observed, and after patterns or similarities are noted, the theorist generates ideas based on these examples. Established theories are tested through research; however, not all theories are equally suited to scientific investigation.  Some theories are complex to try but are still valuable for stimulating debate or providing concepts that have practical applications. Remember that theories are not facts; they are guidelines for investigation and practice, and they gain credibility through research that fails to disprove them.

Psychodynamic Theory

We begin with the often-controversial figure, Sigmund Freud. Freud has been a very influential figure in development; his view of development and psychopathology dominated the field of psychiatry until the growth of behaviorism in the 1950s. His assumptions that personality forms during the first few years of life and that how parents or other caregivers interact with children has a long-lasting impact on children’s emotional states have guided parents, educators, clinicians, and policy-makers for many years. We have only recently begun to recognize that early childhood experiences do not always result in certain personality traits or emotional states. A growing body of literature addresses resiliency in children from harsh backgrounds yet develops without damaging emotional scars (O’Grady and Metz, 1987). Freud has stimulated an enormous amount of research and generated many ideas. Agreeing with Freud’s theory in its entirety is hardly necessary for appreciating the contribution he has made to the field of development.

Sigmund Freud (1856–1939) was a Viennese M. D. who was trained in neurology and asked to work with patients suffering from hysteria, a condition marked by uncontrollable emotional outbursts, fears, and anxiety that had puzzled physicians for centuries. He was also asked to work with women who suffered from physical symptoms and forms of paralysis that had no organic causes. During that time, many people believed that certain individuals were genetically inferior and thus more susceptible to mental illness. Women were thought to be genetically inferior and therefore prone to diseases such as hysteria (which had previously been attributed to a detached womb that was traveling around in the body).

However, after World War I, many soldiers came home with problems similar to hysteria. This called into question the idea of genetic inferiority as a cause of mental illness. Freud began working with hysterical patients and discovered that when they started to talk about some of their life experiences, particularly those that took place in early childhood, their symptoms disappeared. This led him to suggest the first purely psychological explanation for physical problems and mental illness. He proposed that unconscious motives, desires, fears, and anxieties drive our actions. When upsetting memories or thoughts find their way into our consciousness, we develop defenses to shield us from these painful realities. These defense mechanisms include denying a reality, repressing or pushing away sad thoughts, rationalizing or finding a seemingly logical explanation for circumstances, projecting or attributing our feelings to someone else, or outwardly opposing something we inwardly desire (reaction formation). Freud believed that many mental illnesses are a result of a person’s inability to accept reality. Freud emphasized the importance of early childhood experiences in shaping our personality and behavior . In our natural state, we are biological beings. We are driven primarily by instincts. During childhood, however, we become social beings as we learn how to manage our instincts and transform them into socially acceptable behaviors. The parenting the child receives has a powerful impact on the child’s personality development. We will explore this idea further in our discussion of psychosexual development.

Theory of the Mind

Freud believed that most mental processes, motivations, and desires are beyond our awareness. Our consciousness, of which we are aware, represents only the tip of the iceberg that comprises our mental state. The preconscious means that which can easily be called into the conscious mind. During development, our motivations and desires are gradually pushed into the unconscious because raw desires are often unacceptable.

Theory of the Self

As adults, our personality or self consists of three main parts: the id , the ego, and the superego . The id, present at birth, consists of our instincts and drives. It is the part of us that wants immediate gratification. Later in life, it comes to house our deepest, often socially unacceptable desires, such as sex and aggression. It operates under the pleasure principle, which means that the criterion for determining whether something is good or bad is whether it feels good or bad. An infant uses the id self. The ego is the part of the self that develops as we learn that there are limits on what is acceptable and that we often must wait to satisfy our needs. This part of the self is realistic and reasonable. It knows how to make compromises. It operates under the reality principle or the recognition that sometimes gratification must be postponed for practical reasons. It acts as a mediator between the id and the superego and is viewed as the healthiest part of the self.

Defense mechanisms emerge to help a person distort reality so that the truth is less painful. Defense mechanisms include repression, which means pushing the painful thoughts out of consciousness (in other words, thinking about something else). Denial is not accepting the truth or lying to the self. Thoughts such as “It won’t happen to me,” “You’re not leaving,” or “I don’t have a problem with alcohol” are examples. Regression refers to returning to a time when the world felt safer, perhaps reverting to one’s childhood. This is less common than the first two defense mechanisms. Sublimation involves transforming unacceptable urges into more socially acceptable behaviors. For example, a teenager who experiences strong sexual urges uses exercise to redirect those urges into more socially acceptable behavior. Displacement involves taking out frustrations on a safer target. A person who is angry at a boss may take out their frustration on others when driving home or on a spouse upon arrival. Projection is a defense mechanism in which people attribute their unacceptable thoughts to others. If someone is frightened, for example, they accuse someone else of fear. Finally, reaction formation is a defense mechanism in which a person outwardly opposes something they inwardly desire, which they find unacceptable. An example of this might be homophobia or an intense hatred and fear of homosexuality.

This is a partial listing of defense mechanisms suggested by Freud. If the ego is strong, the individual is realistic and accepting of reality and remains more logical, objective, and reasonable. Building ego strength is a significant goal of psychoanalysis (Freudian psychotherapy). So, for Freud, having a big ego is a good thing because it does not refer to being arrogant; it relates to being able to accept reality.

The superego is the part of the self that develops as we learn society’s rules, standards, and values. This part of the self considers the moral guidelines that are a part of our culture. It is a rule-governed part of the self that operates under a sense of guilt (guilt is a social emotion—it is a feeling that others think less of you or believe you to be wrong). If a person violates the superego, they feel guilty. The superego is helpful but can be too strong; in this case, a person might feel overly anxious and guilty about circumstances over which they had no control. Such a person may experience high stress and inhibition levels that keep them from living well. The id is inborn, but the ego and superego develop during our early interactions with others. These interactions occur against a backdrop of learning to resolve early biological and social challenges and play a key role in our personality development.

Psychosexual Stages

Freud believed that development occurs in a series of stages. At each stage, one will either successfully move through that stage and that stage is resolved or will experience challenges and become fixated in that stage. At any of these stages, the child might become “stuck” or fixated if a caregiver either overly indulges or neglects the child’s needs. A fixated adult will continue to try and resolve this later in life. Examples of fixation are given after the presentation of each stage.

From birth through the first year of life, the infant is in the oral stage of psychosexual development. The infant’s needs are met primarily through oral gratification. A baby wishes to suck or chew on any object that comes close to the mouth. Babies explore the world through the mouth and find comfort and stimulation. Psychologically, the infant is in the id. The infant seeks immediate gratification of comfort, warmth, food, and stimulation. If the caregiver meets oral needs consistently, the child will move away from this stage and progress to the next stage. However, if the caregiver is inconsistent or neglectful, the person may stay in the oral stage. As an adult, the person might not feel good unless involved in some oral activity such as eating, drinking, smoking, nail-biting, or compulsive talking. These actions bring comfort and security when the person feels insecure, afraid, or bored.

During the anal stage, which coincides with toddlerhood (ages 1-3) or mobility and potty training, the child is taught that some urges must be contained and some actions postponed. There are rules about certain functions and when and where they will be carried out. The child is learning a sense of self-control. The ego is being developed.  If the caregiver is highly controlling about potty training (stands over the child waiting for the slightest indication that the child might need to go to the potty and immediately scoops the child up and places him on the potty chair, for example), the child may grow up fearing losing control. He may become fixated in this stage or “anal retentive”—fearful of letting go. Such a person might be extremely neat and clean, organized, reliable, and controlling of others. If the caregiver neglects to teach the child to control urges, he may grow up to be “anal expulsive” or an adult who is messy, irresponsible, and disorganized.

The phallic stage occurs during preschool (ages 3-5) when the child faces a new biological challenge. Freud believed that the child becomes sexually attracted to their opposite-sexed parent. Boys experience the “Oedipal Complex,” in which they become sexually attracted to their mothers but realize that their father is in the way. He is much more powerful. For a while, the boy fears that if he pursues his mother, his father may castrate him (castration anxiety). So rather than risk losing his penis, he gives up his affection for his mother and instead learns to become more like his father, imitating his actions and mannerisms and thereby retaining the role of males in his society. From this experience, the boy learns a sense of masculinity. He also knows what society thinks he should do and experiences guilt if he does not comply. In this way, the superego develops. If he does not resolve this successfully, he may become a “phallic male” or a man who constantly tries to prove his masculinity (about which he is insecure) by seducing women and beating up men! A little girl experiences the “Electra Complex,” in which she develops an attraction for her father but realizes that she cannot compete with her mother, so she gives up that affection and learns to become more like her mother. This is not without some regret, however. Freud believed that the girl feels inferior because she does not have a penis (experiences “penis envy”). But she must resign herself to the fact that she is female and will have to learn her inferior role in society as a female.  However, if she does not resolve this conflict successfully, she may have a weak sense of femininity and grow up to be a “castrating female” who tries to compete with men in the workplace or other areas of life.

During middle childhood (6-12), the child enters the latent stage, focusing their attention outside the family and toward friendships. The biological drives are temporarily quieted (latent), and the child can direct attention to a larger world of friends. If the child can make friends, they will gain confidence. If not, the child may remain a loner or shy away from others, even as an adult.

The final stage of psychosexual development is referred to as the genital stage . From adolescence through adulthood, a person is preoccupied with sex and reproduction. The adolescent experiences rising hormone levels, and the sex drive and hunger drives become very strong. Ideally, the adolescent will rely on the ego to help think logically through these urges without taking actions that might be damaging. An adolescent might learn to redirect their sexual urges into safer activities such as running, for example. Quieting the id with the superego can lead to feeling overly self-conscious and guilty about these urges. Hopefully, the ego is strengthened during this stage, and the adolescent uses reason to manage urges.

Strengths and Weaknesses of Freud’s Theory

Freud’s theory has been heavily criticized for several reasons. One is that it is tough to test scientifically. How can parenting in infancy be traced to personality in adulthood? Are there other variables that might better explain development? The theory is also considered to be sexist in suggesting that women who do not accept an inferior position in society are somehow psychologically flawed. Freud focuses on the darker side of human nature, meaning that much of what determines our actions is unknown. So why do we study Freud? As mentioned above, despite the criticisms, Freud’s assumptions about the importance of early childhood experiences in shaping our psychological selves have found their way into child development, education, and parenting practices. Freud’s theory has heuristic value in providing a framework to elaborate and modify subsequent development theories. Many later theories, particularly behaviorism and humanism, challenged Freud’s views.

Psychosocial Theory

The ego rules.

Erik Erikson (1902–1994) was a student of Freud who believed that relationships, not sex and aggression, were the motivators of development. Erikson’s psychosocial theory of development emphasizes that we are aware of what motivates us throughout life, and the ego has greater importance in guiding our actions than the id (Erikson, 1950; 1968). We make conscious choices, focusing on meeting specific social and cultural needs rather than purely biological ones. Humans are motivated, for instance, by the need to feel that the world is a trustworthy place, that we are capable individuals, that we can contribute to society, and that we have lived meaningful lives. These are all psychosocial problems. Erikson divided the lifespaninto eight stages. In each phase, we have a significant psychosocial task to address.  Erikson believed that our personality continues to take shape throughout our lifespanas we face these challenges in living.  We will discuss each of these stages in length as we explore each period of the life span, but here is a brief overview:

Psychosocial Stages

• Trust vs. mistrust (0-1): the infant must have basic needs met consistently to feel that the world is a trustworthy place.
• Autonomy vs. shame and doubt (1-2): mobile toddlers have newfound freedom. They like to exercise, and by being allowed to do so, they learn some essential independence.
• Initiative vs. guilt (3-5): preschoolers like to initiate activities and emphasize doing things “all by myself.”
• Industry vs. inferiority (6-11): school-aged children focus on accomplishments and begin making comparisons between themselves and their classmates.
• Identity vs. role confusion (adolescence): teenagers are trying to gain a sense of identity as they experiment with various roles, beliefs, and ideas.
• Intimacy vs. isolation (young adulthood): in our 20s and 30s, we are making some of our first long-term commitments in intimate relationships.
• Generativity vs. stagnation (middle adulthood): from the 40s through the early 60s, we focus on being productive at work and home and are motivated by wanting to feel that we’ve contributed to society.
• Integrity vs. despair (late adulthood): we look back on our lives and hope to like what we see—that we have lived well and have a sense of integrity because we lived according to our beliefs.

These eight stages form a foundation for discussions on emotional and social development during the life span. However, remember that these stages or crises can occur more than once. For instance, a person may struggle with a lack of trust beyond infancy under certain circumstances. Erikson’s theory has been criticized for focusing so heavily on stages and assuming that completing one stage is a prerequisite for the subsequent development crisis. His theory also focuses on the social expectations in certain cultures, but not in all. For instance, the idea that adolescence is a time of searching for identity might translate well in the middle-class culture of the United States but not as well in cultures where adulthood coincides with puberty through rites of passage and where adult roles offer fewer choices.

Exploring Behavior

Why do we do what we do.

Learning theories focus on how we respond to events or stimuli rather than emphasizing what motivates our actions. These theories explain how experience can change what we can do or feel.

Classical Conditioning and Emotional Responses

Classical conditioning theory helps us to understand how our responses to one situation become attached to new situations. For example, a smell might remind us of when we were kids (elementary school cafeterias smell like milk and mildew!). Going to a new cafeteria with the same smell might evoke feelings you had when you were in school. Or a song on the radio might remind you of a memorable evening you spent with your first true love. Or, if you hear your entire name (John Wilmington Brewer, for instance) called as you walk across the stage to get your diploma, it makes you tense because it reminds you of how your father used to use your full name when he was mad at you, you’ve been classically conditioned!

Classical conditioning explains how we develop many emotional responses to people or events or our “gut-level” reactions to situations. New situations may bring an old response because the two have become connected. Attachments form in this way. Addictions are affected by classical conditioning, as anyone who’s tried to quit smoking can tell you. When you try to stop, everything that is associated with smoking makes you crave a cigarette.

Ivan Pavlov (1880–1937) was a Russian physiologist interested in studying digestion. As he recorded the salivation his laboratory dogs produced as they ate, he noticed that they began to salivate before the food arrived as the researcher walked down the hall and toward the cage. “This,” he thought, “is not natural!” One would expect a dog to salivate when the food hits their palate automatically, but BEFORE the food comes? Of course, what had happened was . . . you tell me. That’s right! The dogs knew the food was coming because they had learned to associate the footsteps with the food. The key word here is “learned.” A learned response is called a “conditioned” response. Pavlov began to experiment with this “psychic” reflex. For instance, he began to ring a bell before introducing the food. Sure enough, after making this connection several times, the dogs could be made to salivate to the sound of a bell.

Once the bell had become an event to which the dogs had learned to salivate, it was called a conditioned stimulus. The act of salivating to a bell was a response that had also been learned, now termed in Pavlov’s jargon, a conditioned response. Notice that the response, salivation, is the same whether it is conditioned or unconditioned (unlearned or natural). What changed is the stimulus to which the dog salivates. One is natural (unconditioned) and learned (conditioned). Well, enough of Pavlov’s dogs. Who cares? Let’s think about how classical conditioning is used on us. One of the most widespread applications of classical conditioning principles was brought to us by the psychologist John B. Watson.

Watson and Behaviorism

John B. Watson believed most fears and other emotional responses are classically conditioned. He had gained popularity in the 1920s with his expert parenting advice offered to the public. He believed that parents could be taught to help shape their children’s behavior. He tried to demonstrate the power of classical conditioning with his famous experiment with an 18-month-old boy named “Little Albert.” Watson sat Albert down and introduced a variety of seemingly scary objects to him: a burning piece of newspaper, a white rat, etc. But Albert remained curious and reached for all of these things. Watson knew that one of our only inborn fears was the fear of loud noises, so he made a loud noise each time he introduced one of Albert’s favorites, a white rat. After hearing the loud noise paired with the rat several times, Albert soon came to fear it and began to cry when it was introduced. Watson filmed this experiment for posterity and used it to demonstrate that he could help parents achieve any desired outcomes if they would only follow his advice. Watson wrote columns in newspapers and magazines, gaining popularity among parents eager to apply science to household order. Parenting advice was not the legacy Watson left us, however. He made his impact in advertising. After Watson left academia, he went into the business world and showed companies how to tie something that brings a natural positive feeling to their products to enhance sales. Thus, the union of sex and advertising! So, let’s use a much more interesting example than Pavlov’s dogs to check and see if you understand the difference between conditioned and unconditioned stimuli and responses. In the experiment with Little Albert, identify the unconditioned stimulus, the unconditioned response, and, after conditioning, the conditioned stimulus and the conditioned response.

Operant Conditioning and Repeating Actions

Operant conditioning is another learning theory emphasizing a more conscious type of learning than classical conditioning. A person (or animal) does something (operates something) to see what effect it might bring. Simply said, operant conditioning describes how we repeat behaviors because they pay off for us. It is based on a principle authored by a psychologist named Thorndike (1874–1949) called the law of effect. The law of effect suggests that we will repeat an action if a sound effect follows it.

Skinner and Reinforcement

Watch how a pigeon learns through reinforcement:

B. F. Skinner (1904–1990) expanded on Thorndike’s principle and outlined the principles of operant conditioning. Skinner believed that we know best when our actions are reinforced. For example, a child who cleans his room and is supported (rewarded) with a big hug and words of praise is more likely to clean it again than a child whose deed goes unnoticed. Skinner believed that almost anything could be reinforcing. A reinforcer is anything following a behavior that makes it more likely to occur again. It can be something intrinsically rewarding (intrinsic or primary reinforcers), such as food or praise, or rewarding because it can be exchanged for what one wants (such as using money to buy a cookie). Such reinforcers are referred to as secondary reinforcers or extrinsic reinforcers.

Positive and Negative Reinforcement

Sometimes, adding something to the situation reinforces, as in the cases we described above, with cookies, praise, and money. Positive reinforcement involves adding something to the situation to encourage a behavior. Other times, taking something away from a problem can be reinforcing. For example, the loud, annoying buzzer on your alarm clock enables you to get up to turn it off and eliminate the noise. Children whine to get their parents to do something, and often, parents give in to stop the whining. In these instances, negative reinforcement has been used.

Operant conditioning tends to work best if you focus on encouraging a behavior or moving a person in the direction you want them to rather than telling them what not to do. Reinforcers are used to promote a behavior; punishers are used to stop the behavior. A punisher is anything that follows an act and decreases the chance it will reoccur. But often, a punished behavior doesn’t go away. It is suppressed and may reoccur whenever the threat of punishment is removed. For example, a child may not cuss around you because you’ve washed his mouth out with soap, but he may curse around his friends. Or a motorist may only slow down when the trooper is on the side of the freeway. Another problem with punishment is that when a person focuses on punishment, they may find it hard to see what the other does right or well. Punishment is stigmatizing; when punished, some start to see themselves as bad and give up trying to change.

Reinforcement can occur predictably, such as after every desired action is performed, intermittently after the behavior is performed several times, or the first time after a certain amount of time. The schedule of reinforcement has an impact on how long a behavior continues after reinforcement is discontinued. So, a parent who has rewarded a child’s actions each time may find that the child gives up very quickly if a reward is not immediately forthcoming. A lover warmly regarded now and then may continue seeking their partner’s attention long after the partner has tried to break up. Think about the behaviors you may have learned through classical and operant conditioning. You may have learned many things in this way. But sometimes, we learn very complex behaviors quickly and without direct reinforcement. Bandura explains how.

Social Learning Theory

Albert Bandura is a leading contributor to social learning theory. He calls our attention to how many of our actions are not learned through conditioning but learned by watching others (1977). Young children frequently learn behaviors through imitation. Sometimes, particularly when we do not know what else to do, we learn by modeling or copying the behavior of others. On their first day of a new job, an employee might eagerly look at how others are acting and try to act the same way to fit in more quickly. Adolescents struggling with their identity rely heavily on their peers to serve as role models. Newly married couples often rely on roles they may have learned from their parents and begin to act in ways they did not while dating and then wonder why their relationship has changed. Sometimes, we do things because we’ve seen it pay off for someone else. They were operantly conditioned, but we engage in the behavior because we hope it will also pay off for us. This is vicarious reinforcement (Bandura, Ross, and Ross, 1963).

Do Parents Socialize Children, or Do Children Socialize Parents?

Bandura (1986) suggests an interplay between the environment and the individual. We are not just the product of our surroundings; we influence our surroundings. There is an interplay between our personality, how we interpret events, and how they influence us. This concept is called reciprocal determinism. An example of this might be the interplay between parents and children. Parents not only influence their child’s environment, perhaps intentionally through reinforcement, etc., but children influence parents as well. Parents may respond differently with their first child than with their fourth. Perhaps they try to be the perfect parents with their firstborn, but by the time their last child comes along, they have very different expectations of themselves and their child. Our environment creates us, and we make our environment. Other social influences: TV or not TV? Bandura (et al. 1963) began a series of studies examining the impact of television, particularly commercials, on children’s behavior.

Are children more likely to act aggressively when this behavior is modeled? What if they see it being reinforced? Bandura began with an experiment showing children a film of a woman hitting an inflatable clown or “Bobo” doll. Then, the children were allowed into the room where they found the doll and immediately began to hit it. This was without any reinforcement whatsoever. Later, they viewed a woman hitting a real clown, and sure enough, when allowed in the room, they too began to hit the clown! Not only that, but they found new ways to behave aggressively. It’s as if they learned an aggressive role.

Watch Bandura’s Bobo-doll experiment:

Children view far more television today than in the 1960s, so much so that they have been referred to as Generation M (media). Based on a study of a nationally representative sample of over 7,000 8-18-year-olds, the Kaiser Foundation reports that children spend just over 8 hours a day involved with media outside of schoolwork. This includes almost 4 hours of television viewing and over an hour on the computer. Two-thirds have television in their room, and those children watch an average of 1.27 hours more per day than those who do not have television in their bedroom (Kaiser Family Foundation, 2005). The prevalence of violence, sexual content, and messages promoting foods high in fat and sugar in the media are certainly cause for concern and the subjects of ongoing research and policy review. Many children spend even more time on the computer viewing content from the Internet. And the amount of time spent connected to the Internet continues to increase with smartphones that essentially serve as mini-computers. What are the implications of this?

Exploring Cognition

What do we think.

Cognitive theories focus on how our mental processes or cognitions change over time. We will examine the ideas of two cognitive theorists: Jean Piaget and Lev Vygotsky.

Piaget: Changes in Thought with Maturation

Jean Piaget (1896–1980) is one of the most influential cognitive theorists in development. He was inspired to explore children’s ability to think and reason by watching his own children’s development. He was one of the first to recognize and map out how children’s intelligence differs from that of adults. When asked to test children’s IQ, he became interested in this area and began noticing a pattern in their wrong answers! He believed that children’s intellectual skills change over time and that maturation rather than training brings about that change. Children of differing ages interpret the world differently.

Making Sense of the World

Piaget believed we continuously try to maintain cognitive equilibrium, balance, or cohesiveness in what we see and know. Children are more challenged in maintaining this balance because they are constantly confronted with new situations, words, objects, etc. When faced with something new, a child may either fit it into an existing framework ( schema ) and match it with something known ( assimilation ), such as calling all animals with four legs “doggies” because they see the word doggie, or expand the framework of knowledge to accommodate the new situation ( accommodation ) by learning a new word to name the animal more accurately. This is the underlying dynamic in our cognition. Even as adults, we try to “make sense” of new situations by determining whether they fit into our old thinking or need to modify our thoughts.

Stages of Cognitive Development

Piaget outlined four significant stages of cognitive development. Let me briefly mention them here. We will discuss them in detail throughout the course. For about the first two years of life, the child experiences the world primarily through their senses and motor skills. Piaget referred to this type of intelligence as sensorimotor intelligence. During preschool, the child begins to master symbols or words and can think of the world symbolically but not logically. This stage is the preoperational stage of development. The concrete operational stage in middle childhood is marked by an ability to use logic to understand the physical world. In the final formal operational stage, the adolescent learns to think abstractly and use logic in concrete and abstract ways.

Criticisms of Piaget’s Theory

Piaget has been criticized for overemphasizing physical maturation’s role in cognitive development and underestimating the role of culture and interaction (or experience) in cognitive development. Looking across cultures reveals considerable variation in what children can do at various ages. Piaget may have underestimated what children are capable of given the right circumstances.

Vygotsky: Changes in Thought with Guidance

Lev Vygotsky (1896–1934) was a Russian psychologist who wrote in the early 1900s but whose work was discovered in the United States in the 1960s but became more widely known in the 1980s. Vygotsky differed from Piaget in that he believed that a person not only has a set of abilities but also a set of potential abilities that can be realized if given the proper guidance from others. His sociocultural theory emphasizes the importance of culture and interaction in developing cognitive skills. He believed that through guided participation, known as scaffolding, with a teacher or capable peer, a child can learn cognitive skills within a specific range, known as the zone of proximal development. Have you ever taught a child to perform a task? Maybe it was brushing their teeth or preparing food. Chances are you spoke to them and described what you were doing while you demonstrated the skill and let them work with you all through the process. You assisted them when they seemed to need it, but once they knew what to do, you stood back and let them go. This is scaffolding and can be seen demonstrated throughout the world. Educators have also adopted this approach to teaching. Rather than assessing students on what they are doing, they should be understood in terms of what they can do with the proper guidance. You can see how Vygotsky would be very popular with modern-day educators. We will discuss Vygotsky in greater depth in upcoming lessons.

Putting It All Together: Ecological Systems Model

Urie Bronfenbrenner (1917–2005) provides a model of human development that addresses its many influences. Bronfenbrenner recognized that larger social forces influence human interaction and that understanding those forces is essential for understanding an individual. The individual is impacted by microsystems such as parents or siblings who have direct, significant contact with the person. The cognitive and biological state of the individual also modifies the input of those. These influence the person’s actions, which affect systems operating on them. The mesosystem includes larger organizational structures such as school, family, or religion. These institutions impact the microsystems just described. For example, religious teachings and traditions may guide the child’s family’s actions or create a climate that makes the family feel stigmatized, indirectly impacting the child’s view of self and others. The philosophy of the school system, daily routine, assessment methods, and other characteristics can affect the child’s self-image, growth, sense of accomplishment, and schedule, impacting the child physically, cognitively, and emotionally. These mesosystems both influence and are influenced by the larger contexts of community referred to as the ecosystem . A community’s values, history, and economy can impact its organizational structures. The community is influenced by macrosystems and cultural elements such as global economic conditions, war, technological trends, values, philosophies, and a society’s responses to the worldwide community. In sum, a child’s experiences are shaped by larger forces such as the family, schools, religion, and culture. All of this occurs in a historical context or chronosystem. Bronfenbrenner’s model helps us combine each of the other theories described above and gives us a perspective that brings it all together.

Research Designs

Observational studies involve watching and recording the actions of participants. This may occur in a natural setting, such as observing children playing at a park or behind a one-way glass while children play in a laboratory playroom. The researcher may follow a checklist and record the frequency and duration of events (perhaps how many conflicts occur among 2-year-olds) or may observe and register as much as possible about an event as a participant (such as attending an Alcoholics Anonymous meeting and recording the slogans on the walls, the structure of the meeting, the expressions commonly used, etc.). The researcher may be a participant or a non-participant. What would be the strengths of being a participant? What would be the weaknesses? Consider the strengths and weaknesses of not participating. In general, observational studies have the strength of allowing the researcher to see how people behave rather than relying on self-reporting. What people do and what they say they do are often very different. A significant weakness of observational studies is that they do not allow the researcher to explain causal relationships. Yet, observational studies are helpful and widely used when studying children. Children tend to change their behavior when they know they are being watched (the Hawthorne effect ) and may not survey well.

Experiments  are designed to test  hypotheses  (or specific statements about the relationship between  variables ) in a controlled setting to explain how certain factors or events produce outcomes. A variable is anything that changes in value. Concepts are operationalized or transformed into variables in research, meaning that the researcher must specify precisely what will be measured in the study. For example, suppose we are interested in studying marital satisfaction. In that case, we have to specify what marital satisfaction means or what we will use as an indicator of marital satisfaction. What is something measurable that would indicate some level of marital satisfaction? Would it be the amount of time couples spend together each day? Or eye contact during a discussion about money? Or maybe a subject’s score on a marital satisfaction scale? Each of these is measurable but may not be equally valid or accurate indicators of marital satisfaction. What do you think? These are the kinds of considerations researchers must make when working through the design.

Three conditions must be met to establish cause and effect. Experimental designs help meet these conditions.

The independent and dependent variables must be related. In other words, the other changes in response when one is altered. (The independent variable is something altered or introduced by the researcher. The dependent variable is the outcome or the factor affected by the introduction of the independent variable. For example, if we are looking at the impact of exercise on stress levels, the independent variable would be exercise; the dependent variable would be stress.)

The cause must come before the effect. Experiments involve measuring subjects on the dependent variable before exposing them to the independent variable (establishing a baseline). So, we would measure the subjects’ stress levels before introducing the exercise and then again after the exercise to see if there was a change in stress levels. (Observational and survey research does not always allow us to look at the timing of these events, making understanding causality problematic with these designs.)

The cause must be isolated.  The researcher must ensure that no outside, perhaps unknown, variables are causing the effect we see. The experimental design helps make this possible. In an experiment, we would ensure that our subjects’ diets were constant throughout the exercise program. Otherwise, diet rather than exercise might create a change in stress levels.

A basic experimental design involves beginning with a sample (or population subset) and randomly assigning subjects to one of two experimental or control groups . The experimental group will be exposed to an independent variable or condition the researcher introduces as a potential cause of an event. The control group is going to be used for comparison. It will have the same experience as the experimental group but will not be exposed to the independent variable. After exposing the experimental group to the independent variable, the two groups are measured again to see if a change has occurred. If so, we are better positioned to suggest that the independent variable caused the shift in the dependent variable . The basic experimental model looks like this:

The experimental design’s primary advantage is that it helps establish cause-and-effect relationships. A disadvantage of this design is the difficulty translating much of what concerns us about human behavior into a laboratory setting. I hope this brief description of experimental design helps you appreciate the difficulty and the rigor of experimenting.

Case studies  involve exploring a single case or situation in great detail. Information may be gathered using observation, interviews, testing, or other methods to uncover as much as possible about a person or situation. Case studies are helpful when investigating unusual situations such as brain trauma or children reared in isolation. They are often used by clinicians who conduct case studies as part of their regular practice when gathering information about a client or patient coming in for treatment. Case studies can be used to explore areas about which little is known and can provide rich detail about situations or conditions. However, the findings from case studies cannot be generalized or applied to larger populations because cases are not randomly selected, and no control group is used for comparison. (Read “The Man Who Mistook His Wife for a Hat” by Dr. Oliver Sacks as an excellent example of the case study approach.)

Surveys are familiar to most people because they are so widely used. Surveys enhance accessibility to subjects because they can be conducted in person, over the phone, through the mail, or online. A survey involves asking a standard set of questions to subjects. In a highly structured survey, subjects must choose from a response set such as “strongly disagree, disagree, undecided, agree, strongly agree” or “0, 1-5, 6-10, etc.” Surveys are commonly used by sociologists, marketing researchers, political scientists, therapists, and others to gather information on many independent and dependent variables in a relatively short period. Surveys typically yield surface information on various factors but may not allow for an in-depth understanding of human behavior. Of course, surveys can be designed in several ways. They may include forced choice and  semi-structured questions in which the researcher allows the respondent to describe or give details about specific events. One of the most challenging aspects of designing a good survey is wording questions unbiasedly and asking the right questions so that respondents can give a clear response rather than choosing “undecided” each time. Knowing that 30% of respondents are undecided is of little use! So, much time and effort should be spent constructing survey items. One of the benefits of having forced-choice items is that each response is coded so that the results can be quickly entered and analyzed using statistical software. Analysis takes much longer when respondents give lengthy responses that must be interpreted differently. Surveys help examine stated values, attitudes, and opinions and report on practices. However, they are based on self-report or what people say they do rather than on observation, which can limit accuracy.

Secondary/content analysis involves analyzing information that has already been collected or examining documents or media to uncover attitudes, practices, or preferences. Several data sets are available to those who wish to conduct this type of research. For example, the U.S. Census Data is known and widely used to look at trends and changes taking place in the United States (go to the US Census and check it out). Several other agencies collect data on family life, sexuality, and many other areas of interest in human development (for example, go to the KFF Foundation and see what you find on healthcare, insurance, statistics, and policy). The researcher conducting secondary analysis does not have to recruit subjects but does need to know the quality of the information collected in the original study.

Content analysis involves looking at media such as old texts, pictures, commercials, lyrics, or other materials to explore cultural patterns or themes. An example of content analysis is Aries’s classic history of childhood (1962) called “Centuries of Childhood,” or the analysis of television commercials for sexual or violent content. Passages in text or programs that air can also be randomly selected for analysis. Again, one advantage of analyzing such work is that the researcher does not have to go through the time and expense of finding respondents. Still, the researcher cannot know how accurately the media reflects the actions and sentiments of the population.

Developmental designs are techniques used in lifespan research (and other areas). These techniques examine how age, cohort, gender, and social class impact development. Cross-sectional research begins with a sample representing a cross-section of the population. Respondents who vary in age, gender, ethnicity, and social class might be asked to complete a survey about television program preferences or attitudes toward Internet use. The attitudes of males and females could then be compared to attitudes based on age. In cross-sectional research, respondents are measured only once. This method is much less expensive than longitudinal research but does not allow the researcher to distinguish between the impact of age and the cohort effect. Different attitudes about the Internet, for example, might not be altered by a person’s biological age as much as their life experiences as cohort members.

Longitudinal research involves beginning with a group of people who may be of the same age and background and measuring them repeatedly over a long period. One of the benefits of this type of research is that people can be followed through time and be compared with them when they were younger. A problem with this type of research is that it is costly, and subjects may drop out over time. (The film 49 Up is an example of following individuals over time. You see how people change physically, emotionally, and socially through time.) What would be the drawbacks of being in a longitudinal study? What about 49 Up? Would you want to be filmed every seven years? What would be the advantages and disadvantages? Can you imagine why some would continue and others would drop out of the project?

Cross-sequential research combines aspects of the previous two techniques, beginning with a cross-sectional sample and measuring them over time. This is the perfect model for looking at age, gender, social class, and ethnicity. However, the drawbacks of high costs and attrition are here as well.

Bandura, A. (1977). Social learning theory. New York: General Learning Press.

Bandura, A. (1986). Social foundations of thought and action; A social-cognitive theory. Upper Saddle River, NJ: Prentice Hall.

Bandura, A, Ross, D. &. Ross S. (1963). Imitation of film-mediated aggressive models. Journal of Abnormal and Social Psychology 66:3-11.

Bronfenbrenner, U. (1979). The ecology of human development: Experiments by nature and design. Cambridge, MA: Harvard University Press.

Erikson, E. H. (1950). Childhood and society. New York: Norton.

Erikson, E. H. (1968). Identity, youth, and crisis. New York: Norton.

O’Grady, D. & Metz, J. (1987). Resilience in children at high risk for psychological disorder. Journal of Pediatric Psychology 12(1):3-23.

Piaget, J. (1929). The child’s conception of the world. NY: Harcourt, Brace Jovanovich.

Attribution

From Developmental Psychology by Bill Pelz, CC-BY.  Materials adapted from the course PSYC 200–Lifespan Psychology. Authored by : Laura Overstreet.  Located at :  http://opencourselibrary.org/econ-201/ .  License :  CC BY: Attribution. 

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2.4 Developing a Hypothesis

Learning objectives.

• Distinguish between a theory and a hypothesis.
• Discover how theories are used to generate hypotheses and how the results of studies can be used to further inform theories.
• Understand the characteristics of a good hypothesis.

Theories and Hypotheses

Before describing how to develop a hypothesis it is imporant to distinguish betwee a theory and a hypothesis. A  theory  is a coherent explanation or interpretation of one or more phenomena. Although theories can take a variety of forms, one thing they have in common is that they go beyond the phenomena they explain by including variables, structures, processes, functions, or organizing principles that have not been observed directly. Consider, for example, Zajonc’s theory of social facilitation and social inhibition. He proposed that being watched by others while performing a task creates a general state of physiological arousal, which increases the likelihood of the dominant (most likely) response. So for highly practiced tasks, being watched increases the tendency to make correct responses, but for relatively unpracticed tasks, being watched increases the tendency to make incorrect responses. Notice that this theory—which has come to be called drive theory—provides an explanation of both social facilitation and social inhibition that goes beyond the phenomena themselves by including concepts such as “arousal” and “dominant response,” along with processes such as the effect of arousal on the dominant response.

Outside of science, referring to an idea as a theory often implies that it is untested—perhaps no more than a wild guess. In science, however, the term theory has no such implication. A theory is simply an explanation or interpretation of a set of phenomena. It can be untested, but it can also be extensively tested, well supported, and accepted as an accurate description of the world by the scientific community. The theory of evolution by natural selection, for example, is a theory because it is an explanation of the diversity of life on earth—not because it is untested or unsupported by scientific research. On the contrary, the evidence for this theory is overwhelmingly positive and nearly all scientists accept its basic assumptions as accurate. Similarly, the “germ theory” of disease is a theory because it is an explanation of the origin of various diseases, not because there is any doubt that many diseases are caused by microorganisms that infect the body.

A  hypothesis , on the other hand, is a specific prediction about a new phenomenon that should be observed if a particular theory is accurate. It is an explanation that relies on just a few key concepts. Hypotheses are often specific predictions about what will happen in a particular study. They are developed by considering existing evidence and using reasoning to infer what will happen in the specific context of interest. Hypotheses are often but not always derived from theories. So a hypothesis is often a prediction based on a theory but some hypotheses are a-theoretical and only after a set of observations have been made, is a theory developed. This is because theories are broad in nature and they explain larger bodies of data. So if our research question is really original then we may need to collect some data and make some observation before we can develop a broader theory.

Theories and hypotheses always have this  if-then  relationship. “ If   drive theory is correct,  then  cockroaches should run through a straight runway faster, and a branching runway more slowly, when other cockroaches are present.” Although hypotheses are usually expressed as statements, they can always be rephrased as questions. “Do cockroaches run through a straight runway faster when other cockroaches are present?” Thus deriving hypotheses from theories is an excellent way of generating interesting research questions.

But how do researchers derive hypotheses from theories? One way is to generate a research question using the techniques discussed in this chapter  and then ask whether any theory implies an answer to that question. For example, you might wonder whether expressive writing about positive experiences improves health as much as expressive writing about traumatic experiences. Although this  question  is an interesting one  on its own, you might then ask whether the habituation theory—the idea that expressive writing causes people to habituate to negative thoughts and feelings—implies an answer. In this case, it seems clear that if the habituation theory is correct, then expressive writing about positive experiences should not be effective because it would not cause people to habituate to negative thoughts and feelings. A second way to derive hypotheses from theories is to focus on some component of the theory that has not yet been directly observed. For example, a researcher could focus on the process of habituation—perhaps hypothesizing that people should show fewer signs of emotional distress with each new writing session.

Among the very best hypotheses are those that distinguish between competing theories. For example, Norbert Schwarz and his colleagues considered two theories of how people make judgments about themselves, such as how assertive they are (Schwarz et al., 1991) [1] . Both theories held that such judgments are based on relevant examples that people bring to mind. However, one theory was that people base their judgments on the  number  of examples they bring to mind and the other was that people base their judgments on how  easily  they bring those examples to mind. To test these theories, the researchers asked people to recall either six times when they were assertive (which is easy for most people) or 12 times (which is difficult for most people). Then they asked them to judge their own assertiveness. Note that the number-of-examples theory implies that people who recalled 12 examples should judge themselves to be more assertive because they recalled more examples, but the ease-of-examples theory implies that participants who recalled six examples should judge themselves as more assertive because recalling the examples was easier. Thus the two theories made opposite predictions so that only one of the predictions could be confirmed. The surprising result was that participants who recalled fewer examples judged themselves to be more assertive—providing particularly convincing evidence in favor of the ease-of-retrieval theory over the number-of-examples theory.

Theory Testing

The primary way that scientific researchers use theories is sometimes called the hypothetico-deductive method  (although this term is much more likely to be used by philosophers of science than by scientists themselves). A researcher begins with a set of phenomena and either constructs a theory to explain or interpret them or chooses an existing theory to work with. He or she then makes a prediction about some new phenomenon that should be observed if the theory is correct. Again, this prediction is called a hypothesis. The researcher then conducts an empirical study to test the hypothesis. Finally, he or she reevaluates the theory in light of the new results and revises it if necessary. This process is usually conceptualized as a cycle because the researcher can then derive a new hypothesis from the revised theory, conduct a new empirical study to test the hypothesis, and so on. As  Figure 2.2  shows, this approach meshes nicely with the model of scientific research in psychology presented earlier in the textbook—creating a more detailed model of “theoretically motivated” or “theory-driven” research.

Figure 2.2 Hypothetico-Deductive Method Combined With the General Model of Scientific Research in Psychology Together they form a model of theoretically motivated research.

As an example, let us consider Zajonc’s research on social facilitation and inhibition. He started with a somewhat contradictory pattern of results from the research literature. He then constructed his drive theory, according to which being watched by others while performing a task causes physiological arousal, which increases an organism’s tendency to make the dominant response. This theory predicts social facilitation for well-learned tasks and social inhibition for poorly learned tasks. He now had a theory that organized previous results in a meaningful way—but he still needed to test it. He hypothesized that if his theory was correct, he should observe that the presence of others improves performance in a simple laboratory task but inhibits performance in a difficult version of the very same laboratory task. To test this hypothesis, one of the studies he conducted used cockroaches as subjects (Zajonc, Heingartner, & Herman, 1969) [2] . The cockroaches ran either down a straight runway (an easy task for a cockroach) or through a cross-shaped maze (a difficult task for a cockroach) to escape into a dark chamber when a light was shined on them. They did this either while alone or in the presence of other cockroaches in clear plastic “audience boxes.” Zajonc found that cockroaches in the straight runway reached their goal more quickly in the presence of other cockroaches, but cockroaches in the cross-shaped maze reached their goal more slowly when they were in the presence of other cockroaches. Thus he confirmed his hypothesis and provided support for his drive theory. (Zajonc also showed that drive theory existed in humans (Zajonc & Sales, 1966) [3] in many other studies afterward).

Incorporating Theory into Your Research

When you write your research report or plan your presentation, be aware that there are two basic ways that researchers usually include theory. The first is to raise a research question, answer that question by conducting a new study, and then offer one or more theories (usually more) to explain or interpret the results. This format works well for applied research questions and for research questions that existing theories do not address. The second way is to describe one or more existing theories, derive a hypothesis from one of those theories, test the hypothesis in a new study, and finally reevaluate the theory. This format works well when there is an existing theory that addresses the research question—especially if the resulting hypothesis is surprising or conflicts with a hypothesis derived from a different theory.

To use theories in your research will not only give you guidance in coming up with experiment ideas and possible projects, but it lends legitimacy to your work. Psychologists have been interested in a variety of human behaviors and have developed many theories along the way. Using established theories will help you break new ground as a researcher, not limit you from developing your own ideas.

Characteristics of a Good Hypothesis

There are three general characteristics of a good hypothesis. First, a good hypothesis must be testable and falsifiable . We must be able to test the hypothesis using the methods of science and if you’ll recall Popper’s falsifiability criterion, it must be possible to gather evidence that will disconfirm the hypothesis if it is indeed false. Second, a good hypothesis must be  logical. As described above, hypotheses are more than just a random guess. Hypotheses should be informed by previous theories or observations and logical reasoning. Typically, we begin with a broad and general theory and use  deductive reasoning to generate a more specific hypothesis to test based on that theory. Occasionally, however, when there is no theory to inform our hypothesis, we use  inductive reasoning  which involves using specific observations or research findings to form a more general hypothesis. Finally, the hypothesis should be  positive.  That is, the hypothesis should make a positive statement about the existence of a relationship or effect, rather than a statement that a relationship or effect does not exist. As scientists, we don’t set out to show that relationships do not exist or that effects do not occur so our hypotheses should not be worded in a way to suggest that an effect or relationship does not exist. The nature of science is to assume that something does not exist and then seek to find evidence to prove this wrong, to show that really it does exist. That may seem backward to you but that is the nature of the scientific method. The underlying reason for this is beyond the scope of this chapter but it has to do with statistical theory.

Key Takeaways

• A theory is broad in nature and explains larger bodies of data. A hypothesis is more specific and makes a prediction about the outcome of a particular study.
• Working with theories is not “icing on the cake.” It is a basic ingredient of psychological research.
• Like other scientists, psychologists use the hypothetico-deductive method. They construct theories to explain or interpret phenomena (or work with existing theories), derive hypotheses from their theories, test the hypotheses, and then reevaluate the theories in light of the new results.
• Practice: Find a recent empirical research report in a professional journal. Read the introduction and highlight in different colors descriptions of theories and hypotheses.
• Schwarz, N., Bless, H., Strack, F., Klumpp, G., Rittenauer-Schatka, H., & Simons, A. (1991). Ease of retrieval as information: Another look at the availability heuristic.  Journal of Personality and Social Psychology, 61 , 195–202. ↵
• Zajonc, R. B., Heingartner, A., & Herman, E. M. (1969). Social enhancement and impairment of performance in the cockroach.  Journal of Personality and Social Psychology, 13 , 83–92. ↵
• Zajonc, R.B. & Sales, S.M. (1966). Social facilitation of dominant and subordinate responses. Journal of Experimental Social Psychology, 2 , 160-168. ↵

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Developmental Psychology

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APA endorses the Transparency and Openness Promotion (TOP) Guidelines developed by a community working group in conjunction with the Center for Open Science ( Nosek et al. 2015 ). Empirical research, including meta-analyses, submitted to Developmental Psychology  must at least meet the “requirement” level for all aspects of research planning and reporting. Authors should include a subsection in the method section titled “Transparency and Openness.” This subsection should detail the efforts the authors have made to comply with the TOP Guidelines. 

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• We report how we determined our sample size, all data exclusions (if any), all manipulations, and all measures in the study, and we follow JARS (Appelbaum et al., 2018). All data, analysis code, and research materials are available at [stable link to repository]. Data were analyzed using R, version 4.0.0 (R Core Team, 2020) and the package ggplot , version 3.2.1 (Wickham, 2016). This study’s design and its analysis were not pre-registered.

Data, materials, and code

Authors must state whether data, code, and study materials are posted to a trusted repository and, if so, where to access them, including their location and any limitations on use. If they cannot be made available, authors must state the legal or ethical reasons why they are not available. Trusted repositories adhere to policies that make data discoverable, accessible, usable, and preserved for the long term. Trusted repositories also assign unique and persistent identifiers. Recommended repositories include APA’s repository on the Open Science Framework (OSF), or authors can access a full list of other recommended repositories .

In a subsection titled “Transparency and Openness” at the end of the method section, specify whether and where the data and material will be available or note the legal or ethical reasons for not doing so. For submissions with quantitative or simulation analytic methods, state whether the study analysis code is posted to a trusted repository, and, if so, how to access it (or the legal or ethical reason why it is not available).

• All data have been made publicly available at the [trusted repository name] and can be accessed at [persistent URL or DOI].
• Materials and analysis code for this study are not available because [legal or ethical reason].
• The code behind this analysis/simulation has been made publicly available at the [trusted repository name] and can be accessed at [persistent URL or DOI].

Preregistration of studies and analysis plans

Preregistration of studies and specific hypotheses can be a useful tool for making strong theoretical claims. Likewise, preregistration of analysis plans can be useful for distinguishing confirmatory and exploratory analyses. Investigators are encouraged to preregister their studies and analysis plans prior to conducting the research via a publicly accessible registry system (e.g., OSF , ClinicalTrials.gov, or other trial registries in the WHO Registry Network). There are many available templates; for example, APA, the British Psychological Society, and the German Psychological Society partnered with the Leibniz Institute for Psychology and Center for Open Science to create Preregistration Standards for Quantitative Research in Psychology (Bosnjak et al., 2022).

Articles must state whether or not any work was preregistered and, if so, where to access the preregistration. If any aspect of the study is preregistered, include the registry link in the method section. Preregistrations must be available to reviewers; authors may submit a masked copy via stable link or supplemental material. Links in the method section should be replaced with an identifiable copy on acceptance.

• This study’s design was preregistered; see [STABLE LINK OR DOI].
• This study’s design and hypotheses were preregistered; see [STABLE LINK OR DOI].
• This study’s analysis plan was preregistered; see [STABLE LINK OR DOI].
• This study was not preregistered.

Replications and Registered Reports

Developmental Psychology publishes direct replications. Submissions should include “A Replication of XX Study” in the subtitle of the manuscript as well as in the abstract.

Developmental Psychology also publishes Registered Reports. Registered Reports require a two-step review process. The first step is the submission of the registration manuscript. This is a partial manuscript that includes hypotheses, rationale for the study, experimental design, and methods. The partial manuscript will be reviewed for rigor and methodological approach.

If the partial manuscript is accepted, this amounts to provisional acceptance of the full report regardless of the outcome of the study. The full manuscript will be reviewed for adherence to the preregistered design (deviations should be reported in the manuscript).

Manuscript preparation

Prepare manuscripts according to the Publication Manual of the American Psychological Association using the 7th edition. Manuscripts may be copyedited for bias-free language (see Chapter 5 of the Publication Manual ).

Review APA's Journal Manuscript Preparation Guidelines before submitting your article.

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Journal article

McCauley, S. M., & Christiansen, M. H. (2019). Language learning as language use: A cross-linguistic model of child language development. Psychological Review , 126 (1), 1–51. https://doi.org/10.1037/rev0000126

Authored book

Brown, L. S. (2018). Feminist therapy (2nd ed.). American Psychological Association. https://doi.org/10.1037/0000092-000

Chapter in an edited book

Balsam, K. F., Martell, C. R., Jones. K. P., & Safren, S. A. (2019). Affirmative cognitive behavior therapy with sexual and gender minority people. In G. Y. Iwamasa & P. A. Hays (Eds.), Culturally responsive cognitive behavior therapy: Practice and supervision (2nd ed., pp. 287–314). American Psychological Association. https://doi.org/10.1037/0000119-012

Software/Code citation

Viechtbauer, W. (2010). Conducting meta-analyses in R with the metafor package.  Journal of Statistical Software , 36(3), 1–48. https://www.jstatsoft.org/v36/i03/

Wickham, H. et al., (2019). Welcome to the tidyverse. Journal of Open Source Software, 4 (43), 1686, https://doi.org/10.21105/joss.01686

All data, program code, and other methods must be cited in the text and listed in the references section.

Data set citation

Alegria, M., Jackson, J. S., Kessler, R. C., & Takeuchi, D. (2016). Collaborative Psychiatric Epidemiology Surveys (CPES), 2001–2003 [Data set]. Inter-university Consortium for Political and Social Research. https://doi.org/10.3886/ICPSR20240.v8

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• Download Full Disclosure of Interests Form (PDF, 41KB)

In light of changing patterns of scientific knowledge dissemination, APA requires authors to provide information on prior dissemination of the data and narrative interpretations of the data/research appearing in the manuscript (e.g., if some or all were presented at a conference or meeting, posted on a listserv, shared on a website, including academic social networks like ResearchGate, etc.). This information (2–4 sentences) must be provided as part of the author note.

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In addition, APA Ethical Principles specify that "after research results are published, psychologists do not withhold the data on which their conclusions are based from other competent professionals who seek to verify the substantive claims through reanalysis and who intend to use such data only for that purpose, provided that the confidentiality of the participants can be protected and unless legal rights concerning proprietary data preclude their release" (Standard 8.14).

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• Download Certification of Compliance With APA Ethical Principles Form (PDF, 26KB)

The APA Ethics Office provides the full Ethical Principles of Psychologists and Code of Conduct electronically on its website in HTML, PDF, and Word format. You may also request a copy by emailing or calling the APA Ethics Office (202-336-5930). You may also read "Ethical Principles," December 1992, American Psychologist , Vol. 47, pp. 1597–1611.

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See APA’s Publishing Policies page for more information on publication policies, including information on author contributorship and responsibilities of authors, author name changes after publication, the use of generative artificial intelligence, funder information and conflict-of-interest disclosures, duplicate publication, data publication and reuse, and preprints.

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Koraly Pérez-Edgar, PhD The Pennsylvania State University, United States

Associate editors

Irma Arteaga, PhD University of Missouri, United States

Sheretta T. Butler-Barnes, PhD Washington University in St. Louis, United States

Christopher Beam, PhD University of Southern California, United States

Peter Bos, PhD University of Leiden, The Netherlands 

Natalie Brito, PhD New York University, United States 

Lucas Butler, PhD University of Maryland, United States

Gustavo Carlo, PhD University of California, Irvine, United States

Elisabeth Conradt, PhD University of Utah, United States

Timothy Curby, PhD George Mason University, United States

Judith Danovitch, PhD University of Louisville, United States

John Franchak, PhD University of California, Riverside, United States

Emily Fyfe, PhD Indiana University, United States

Melinda Gonzales Backen, PhD Florida State University, United States

Wendy Gordon, PhD Auburn University, United States

Noa Gueron-Sela, PhD Ben-Gurion University, Israel

Elizabeth Gunderson, PhD Indiana University, United States

Amanda Guyer, PhD University of California, Davis, United States

Larisa Solomon, PhD Columbia University, United States

Lana Karasik, PhD City University of New York, United States

Melissa Kibbe, PhD Boston University, United States

Elizabeth Kiel, PhD Miami University of Ohio, United States

Su Yeong Kim, PhD University of Texas, Austin, United States

Diana Leyva, PhD University of Pittsburgh, United States

Jennifer McDermott, PhD University of Massachusetts, Amherst, United States

Kristine Marceau, PhD Purdue University, United States

Julie Markant, PhD Tulane University, United States

Kalina Michalska, PhD University of California, Riverside, United States

Francisco Palermo, PhD University of Missouri, United States

Carlomagno Panlilio, PhD The Pennsylvania State University, United States

Mikko Peltola, PhD Tampere University, Finland

Gavin Price, PhD Exeter University, United Kingdom

Joanna Williams, PhD Rutgers University, United States

Qing Zhou, PhD University of California, Berkeley, United States

Consulting editors

Melissa Barnett, PhD University of Arizona, United States

Martha Ann Bell, PhD Virginia Tech, United States

Deon Benton, PhD Vanderbilt University, United States

Tashauna Blankenship, PhD University of Massachusetts, Boston, United States

David Bridgett, PhD Northern Illinois University, United States

Rebecca Brooker, PhD Texas A&M University, United States

Samantha Brown, PhD Colorado State University, United States

Claire Cameron, PhD University at Buffalo, United States

Carlos Cardenas-Iniguez, PhD University of Southern California, United States

Rona Carter, PhD, LLP, RYT University of Michigan, United States

Stephen Chen, PhD Wellesley College, United States

Elizabeth Davis, PhD University of California, Riverside, United States

Leah Doane, PhD Arizona State University, United States

Jessica Dollar, PhD University of North Carolina, Greensboro, United States

Robert Duncan, PhD Purdue University, United States

Ari Eason, PhD University of California, Berkeley, United States

Katie Ehrlich, PhD University of Georgia, United States

Paola Escudero, PhD Western Sydney University, Australia

Caitlin Fausey, PhD University of Oregon, United States

Gregory M. Fosco, PhD The Pennsylvania State University, United States

Nicole Gardner-Neblett, PhD University of Michigan, United States

Erica Glasper, PhD Ohio State University, United States

Selin Gulgoz, PhD Fordham University, United States

Ernest Hodges, PhD St. John’s University, United States

Adam Hoffman, PhD Cornell University, United States

Stefanie Höhl, PhD University of Vienna, Austria

Caroline Hornburg, PhD Virginia Tech, United States

Yang Hou, PhD University of Kentucky, United States

Marina Kalashnikova, PhD Basque Center on Cognition, Brain, and Language, Spain

Heather Kirkorian, PhD University of Wisconsin, Madison, United States

Olga Kornienko, PhD George Mason University, United States

Deborah Laible, PhD Lehigh University, United States

Jonathan Lane, PhD Vanderbilt University, United States

Tessa Lansu, PhD Radboud University, Netherlands

Kathryn Leech, PhD University of North Carolina, United States

Ryan Lei, PhD Haverford College, United States

Jeffrey Liew, PhD Texas A&M University, United States

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Eric Lindsey, PhD Penn State Berks, United States

Jessica Lougheed, PhD University of British Columbia, Okanagan, Canada

Alexandra Main, PhD University of California, Merced, United States

Henrike Moll, PhD University of Southern California, United States

Santiago Morales, PhD University of Southern California, United States

Dianna Murray-Close, PhD University of Vermont, United States

Shaylene Nancekivell, PhD University of North Carolina, Greensboro, United States

Justin Parent, PhD Brown University, United States

Livio Provenzi, PhD IRCCS Mondino Foundation, Italy

Laura Quiñones-Camacho, PhD University of Texas, Austin, United States

Rachel Romeo, PhD, CCC-SLP University of Maryland, United States

Samuel Ronfard, EdD University of Toronto, Canada

Kathleen Rudasill, PhD Virginia Commonwealth University, United States

Adena Schachner, PhD University of California, San Diego, United States

Yishan Shen, PhD Texas State University, United States

Cara Streit, PhD University of New Mexico, United States

Cin Cin Tan, PhD University of Toledo, United States

Rachel Thibodeau-Nielson, PhD University of Missouri, United States

Sho Tsuji, PhD University of Tokyo, Japan

Yuuko Uchikoshi, EdD University of California, Davis, United States

Carlos Valiente, PhD Arizona State University, United States

Nicholas Wagner, PhD Boston University, United States

Jinjing Wang, PhD Rutgers University, United States

Jun Wang, PhD Texas A&M University, United States

Christina Weiland, EdD University of Michigan, United States

Eric Wilkey, PhD Louisiana State University, United States

Peer review coordinator

Emily Densmore American Psychological Association

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Special issue of the APA journal Developmental Psychology, Vol. 56, No. 3, March 2020. Articles discuss the impact of emotion-related socialization behaviors on children’s emotion, self-regulation, and developmental outcomes.

Special issue of the APA journal Developmental Psychology, Vol. 55, No. 9, September 2019. The issue is intended to present and highlight examples of innovative recent approaches and thinking to a range of questions about emotional development and to inspire new directions for future research.

Special issue of the APA journal Developmental Psychology, Vol. 53, No. 11, November 2017. The articles examine identity in developmental stages ranging from early childhood to young adulthood, and represent samples from 5 different countries.

Special issue of the APA journal Developmental Psychology, Vol. 49, No. 3, March 2013. The articles pose important questions concerning how children learn from others, what the characteristic signatures of social learning might be, and how this learning changes over time.

Transparency and Openness Promotion

APA endorses the Transparency and Openness Promotion (TOP) Guidelines by a community working group in conjunction with the Center for Open Science ( Nosek et al. 2015 ). The TOP Guidelines cover eight fundamental aspects of research planning and reporting that can be followed by journals and authors at three levels of compliance.

• Level 1: Disclosure—The article must disclose whether or not the materials are posted to a trusted repository.
• Level 2: Requirement—The article must share materials via a trusted repository when legally and ethically permitted (or disclose the legal and/or ethical restriction when not permitted).
• Level 3: Verification—A third party must verify that the standard is met.

At a minimum, empirical research, including meta-analyses, submitted to Developmental Psychology must, at a minimum, meet Level 2 (Requirement) for all aspects of research planning and reporting. Authors should include a subsection in their methods description titled “Transparency and Openness.” This subsection should detail the efforts the authors have made to comply with the TOP Guidelines.

The list below summarizes the minimal TOP requirements of the journal. Please refer to the TOP guidelines for details, and contact the editor (Koraly Pérez-Edgar, PhD) with any further questions. Authors must share data, materials, and code via trusted repositories (e.g., APA’s repository on the Open Science Framework (OSF)). Trusted repositories adhere to policies that make data discoverable, accessible, usable, and preserved for the long term. Trusted repositories also assign unique and persistent identifiers.

We encourage investigators to preregister their studies and to share protocols and analysis plans prior to conducting their research. Clinical trials are studies that prospectively evaluate the effects of interventions on health outcomes, including psychological health. Clinical trials must be registered before enrolling participants on ClinicalTrials.gov or another primary register of the WHO International Clinical Trials Registry Platform (ICTRP) . There are many available preregistration forms (e.g., the APA Preregistration for Quantitative Research in Psychology template, ClininalTrials.gov , or other preregistration templates available via OSF ). Completed preregistration forms should be posted on a publicly accessible registry system (e.g., OSF , ClinicalTrials.gov, or other trial registries in the WHO Registry Network).

The following list presents the eight fundamental aspects of research planning and reporting, the TOP level required by  Developmental Psychology , and a brief description of the journal's policy.

• Citation: Level 2, Requirement—All data, program code, and other methods developed by others must be cited in the text and listed in the references section.
• Data Transparency: Level 2, Requirement—Article states whether the raw and/or processed data on which study conclusions are based are available and either where to access them or the legal or ethical reasons why they are not available.
• Analytic Methods (Code) Transparency: Level 2, Requirement—Article states whether computer code or syntax needed to reproduce analyses in an article is posted to a trusted repository and either how to access it or the legal or ethical reasons why it is not available
• Research Materials Transparency: Level 2, Requirement—Article states whether materials described in the method section are posted to a trusted repository and either how to access them or the legal or ethical reasons why they are not available.
• Design and Analysis Transparency (Reporting Standards): Level 2, Requirement—Article must comply with APA Style Journal Article Reporting Standards (JARS-Quant, JARS-Qual, and/or MARS).
• Study Preregistration: Level 2, Requirement—Article states whether the study design and (if applicable) hypotheses of any of the work reported was preregistered and, if so, how to access it. Authors must submit a masked copy via stable link or supplemental material.
• Analysis Plan Preregistration: Level 2, Requirement—Article states whether any of the work reported preregistered an analysis plan and, if so, how to access it. Authors must submit a masked copy via stable link or supplemental material.
• Replication: Level 3, Verification—The journal publishes replications and Registered Reports.

Other open science initiatives

• Open Science badges: Not offered
• Public significance statements: Offered
• Author contribution statements using CRediT: Required
• Registered Reports: Published
• Replications: Published
• Detailed sample descriptions: Required

Explore open science at APA .

Inclusive study designs

• Registered Reports

Definitions and further details on inclusive study designs are available on the Journals EDI homepage .

Inclusive reporting standards

• Bias-free language and community-driven language guidelines (required)
• Author contribution roles using CRediT (required)
• Data sharing and data availability statements (required)
• Impact statements (required)
• Participant sample descriptions (required)

More information on this journal’s reporting standards is listed under the submission guidelines tab .

Pathways to authorship and editorship

Editorial fellowships.

Editorial fellowships for this journal will begin in 2023.

Other EDI offerings

Orcid reviewer recognition.

Open Research and Contributor ID (ORCID) Reviewer Recognition provides a visible and verifiable way for journals to publicly credit reviewers without compromising the confidentiality of the peer-review process. This journal has implemented the ORCID Reviewer Recognition feature in Editorial Manager, meaning that reviewers can be recognized for their contributions to the peer-review process.

Masked peer review

This journal offers masked peer review (where both the authors’ and reviewers’ identities are not known to the other). Research has shown that masked peer review can help reduce implicit bias against traditionally female names or early-career scientists with smaller publication records (Budden et al., 2008; Darling, 2015).

Editor Spotlight

• Read the January 2023 editorial by Editor Koraly Pérez-Edgar
• Read an interview with Editor Koraly Pérez-Edgar, PhD

From APA Journals Article Spotlight ®

• Does children's biological functioning predict parenting behavior?
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Theories of Child Development and Their Impact on Early Childhood Education and Care

• Published: 29 October 2021
• Volume 51 , pages 15–30, ( 2023 )

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• Olivia N. Saracho   ORCID: orcid.org/0000-0003-4108-7790 1  

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Developmental theorists use their research to generate philosophies on children’s development. They organize and interpret data based on a scheme to develop their theory. A theory refers to a systematic statement of principles related to observed phenomena and their relationship to each other. A theory of child development looks at the children's growth and behavior and interprets it. It suggests elements in the child's genetic makeup and the environmental conditions that influence development and behavior and how these elements are related. Many developmental theories offer insights about how the performance of individuals is stimulated, sustained, directed, and encouraged. Psychologists have established several developmental theories. Many different competing theories exist, some dealing with only limited domains of development, and are continuously revised. This article describes the developmental theories and their founders who have had the greatest influence on the fields of child development, early childhood education, and care. The following sections discuss some influences on the individuals’ development, such as theories, theorists, theoretical conceptions, and specific principles. It focuses on five theories that have had the most impact: maturationist, constructivist, behavioral, psychoanalytic, and ecological. Each theory offers interpretations on the meaning of children's development and behavior. Although the theories are clustered collectively into schools of thought, they differ within each school.

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The author is grateful to Mary Jalongo for her expert editing and her keen eye for the smallest details.

Although Watson was the first to maintain explicitly that psychology was a natural science, behaviorism in both theory and practice had originated much earlier than 1913. Watson offered a vital incentive to behaviorism, but several others had started the process. He never stated to have created “behavioral psychology.” Some behaviorists consider him a model of the approach rather than an originator of behaviorism (Malone, 2014 ). Still, his presence has significantly influenced the status of present psychology and its development.

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Saracho, O.N. Theories of Child Development and Their Impact on Early Childhood Education and Care. Early Childhood Educ J 51 , 15–30 (2023). https://doi.org/10.1007/s10643-021-01271-5

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Developmental Origins of Health and Disease: Brief History of the Approach and Current Focus on Epigenetic Mechanisms

Pathik d. wadhwa.

1 Department of Pediatrics, University of California, Irvine, School of Medicine, Irvine, California

2 Department of Psychiatry & Human Behavior, University of California, Irvine, School of Medicine, Irvine, California

Claudia Buss

Sonja entringer, james m. swanson.

“Barker’s hypothesis” emerged almost 25 years ago from epidemiological studies of birth and death records that revealed a high geographic correlation between rates of infant mortality and certain classes of later adult deaths as well as an association between birthweight and rates of adult death from ischemic heart disease. These observations led to a theory that undernutrition during gestation was an important early origin of adult cardiac and metabolic disorders due to fetal programming that permanently shaped the body’s structure, function, and metabolism and contributed to adult disease. This theory stimulated interest in the fetal origins of adult disorders, which expanded and coalesced ~5 years ago with the formation of an international society for developmental origins of health and disease (DOHaD). Here we review a few examples of the many emergent themes of the DOHaD approach, including theoretical advances related to predictive adaptive responses of the fetus to a broad range of environmental cues, empirical observations of effects of overnutrition and stress during pregnancy on outcomes in childhood and adulthood, and potential epigenetic mechanisms that may underlie these observations and theory. Next, we discuss the relevance of the DOHaD approach to reproductive medicine. Finally, we consider the next steps that might be taken to apply, evaluate, and extend the DOHaD approach.

FROM EPIDEMIOLOGICAL OBSERVATIONS TO THE FETAL ORIGINS HYPOTHESIS

The Developmental Origins of Health and Disease (DOHaD) approach evolved from epidemiological studies of infant and adult mortality. A trio of articles in The Lancet by Barker and colleagues 1 – 3 represent perhaps the most influential early publications in this area that led to the fetal origins hypothesis (often called “Barker’s hypothesis”). There are many reviews of Barker’s hypothesis, and one of the best is provided by Barker himself, who summarized the genesis of the developmental origins hypothesis. 4 The main points are best described by quotes from these original sources, which we provide later.

Barker 4 gives a personal account of a program of epidemiological research of the geographic distributions of diseases across local authorities of England and Wales, which provided the countrywide data used by Barker et al 1 to show a large positive geographic correlation (~0.7) for standardized rates for infant mortality from 1921 to 1925 and ischemic heart disease from 1968 to 1978. An interpretation of this relationship was based on several factors: the association of neonatal deaths in the 1920 with low birthweight, the dependence on adverse intrauterine rather than postnatal factors, the paradoxical rise in heart disease with rising prosperity but lower rates in the most prosperous locations, a review of the literature on maternal and infant nutrition, and other factors. This led to the insight and hypothesis that the geographic relationship of infant and adults death rates “reflects variations in nutrition in early life, which are expressed pathologically on exposure to later dietary influences” (p. 1081).

According to Barker’s 4 account, the next step of investigation “required studies of a kind that had not hitherto been carried out” (p. 415). This was initiated within a sample of adults (men born from 1911 to 1930 in Hertfordshire) with good records of size at birth, weight in infancy, and death from ischemic health disease, which Barker et al 2 used to confirm (in individuals) the deductions from the geographic study: Men with the lowest birthweights had the highest death rates, those with the highest birthweights had the lowest death rates, and standardized death rates fell steeply with increasing weight at 1 year of age. This led to the hypothesis that “an environment which produces poor fetal and infant growth is followed by an adult environment that determines high risk for ischemic heart disease” (p. 579).

To develop the hypothesis further, Baker et al 3 reviewed how fetal undernutrition at different stages of gestation can be linked to different birth phenotypes, each linked to adaptations associated with changes in concentrations of placental and fetal hormone and later with different metabolic abnormalities in adulthood. This integration proposed that “undernutrition during gestation reprograms the relationship between glucose and insulin and between growth hormone and IGF [insulin-like growth factor]” (p. 940), which permanently changes the body’s structure, function and metabolism that increases risk for coronary heart disease in later life.

FROM FETAL ORIGINS OF ADULT DISEASE TO DEVELOPMENTAL ORIGINS OF HEALTH AND DISEASE

Barker’s hypothesis stimulated a great deal of worldwide interest and activity in the area of developmental plasticity, Gillman et al 5 summarized in a report of the meetings of the World Congress on Fetal Origins of Adult Disease that were convened in 2001 (Mumbai, India) and 2003 (Brighton, United Kingdom) and the transition to DOHaD that was formed subsequently “to recognize the broader scope of developmental cues, extending from the oocyte to the infant and beyond, and the concept that the early life environment has widespread consequences for later health” (p. 625). The DOHaD society has sponsored meetings in 2005 (Toronto, Ontario, Canada), 2006 (Utrecht, The Netherlands), 2007 (Perth, Western Australia), and 2009 (Santiago, Chile), and these international congresses provided an important forum for exchange of ideas and progress in this rapidly expanding field ( www.dohadsoc.org ).

Here we review some of the expanded themes, including: (1) the development of theory based on the concept of predictive adaptive responses of the fetus to a variety of environmental cues and consequences of mismatch between prenatal and postnatal environments, (2) the emphasis on the fetal origins of obesity and overnutrition as well as undernutrition during gestation and in infancy as pathways into obesity in childhood and adulthood, (3) the evaluation of psychobiological effects of stress during pregnancy on fetal development and later outcomes, and (4) the consideration of epigenetic mechanisms to account for some of the observations based on the DOHaD approach.

The field is now so large that a selective review is necessary. For relevance to the topic of reproductive medicine, we chose to focus our review on important details from three specialized research programs (the Southampton Women’s Survey (SWS), Project VIVA, and the Behavioral Perinatology Research Program) that emphasize prospective evaluations of fetal development during pregnancy.

The Southampton Women’s Survey: Background and Current Status

Barker and collaborators developed the first generation of theories to account for the observations of correlations of fetal and adult death rates across geographic locations 1 and birthweight and ischemic heart disease death rates across individuals, 2 which included the “thrifty phenotype” theory of Hales and Barker 6 and the “developmental plasticity” theory of Bateson et al. 7 With this scientific background (see www.mrc.soton.ac.uk ), the next stage of a program of research at the University of Southampton focused on data from cohorts of individuals born in the first half of the 20th century. Using data from one of these cohorts, Roseboom et al 8 investigated effects of timing of fetal undernutrition based on the Dutch cohort exposed to the 1944–1945 famine at the end of World War II and showed that fetal undernutrition may affect different organs of the body depending on different critical phases of development (i.e., in the Dutch famine, those individuals conceived before the famine and exposed to an energy-poor fetal environment late in gestation as adults had increased risk for insulin resistance and impaired glucose tolerance, but those conceived during the famine as adults had increased risk for high serum cholesterol and coronary heart disease). Using data from another cohort, Barker et al 9 investigated the trajectory of growth during infancy and childhood in the Helsinki 1934 to 1944 Birth Cohort (see Eriksson et al 10 ) and showed that adult outcomes were moderated by the tempo of growth in infancy and childhood as well as by fetal growth and birthweight (i.e., the risk of coronary events in adulthood was more strongly related to the tempo of childhood body mass index [BMI] gain from ages 2 to 11 years than to BMI itself at any other age).

This program of research also initiated a new a cohort study of contemporary births. Initial goals were to directly test some of the assumptions of the DOHaD approach (i.e., documentation of adaptations occurring in the fetus when undernourished, including changes in metabolism, alterations in hormone production and tissue sensitivity to these alterations, and changes in the relative growth rates of organs and structures of the body). The SWS started with interviews of 12,500 young female residents of Southampton to obtained measures of prepregnancy characteristics, followed by detailed, prospective evaluation of this cohort that was described by Inskip et al. 11 According to the SWS protocol, detailed measures were obtained of fetal development during conceptions and gestations that produced 3,000 live births, of birth phenotypes, and of outcomes in infancy and childhood. The ambitious goals of the SWS include evaluation of (1) influences of a mother’s diet, body composition, and endocrine profile on fetal growth, placental, and fetal adaptive responses, and (2) interactions of maternal and intrauterine factors with genes and postnatal environments of offspring that influence growth in infancy, pathways that lead to poor adult health, and risk factors for diseases in childhood (obesity, cardiorespiratory function, and asthma) and adulthood (coronary heart disease, type 2 diabetes, and osteoporosis).

An impressive list of publications from 2004 to 2009 is available from the SWS section of the MRC Epidemiology Resource Centre Web site ( http://www.mrc.soton.ac.uk/index.asp?page=4 ). Two examples from this research program are described here to address methodological issues that are critical for the evaluation of some basic assumptions of the DOHaD approach (e.g., the tracking of nutrients and oxygen supply by the measurement of fetal blood flow 12 and the characterization of infant size by measurement of body composition 13 ). These are crucial measures in the theory of developmental plasticity or predictive adaptive response, which predicts that maternal diet may regulate blood flow to developing organs (i.e., to the brain versus the liver) and may elicit fetal programming that affects body composition at birth (fat mass versus lean mass). Haugen et al 12 evaluated the effects of maternal adiposity and diet in 381 low-risk pregnancies in the SWS at 36 weeks of gestation using Doppler ultrasound to estimate blood flow in the umbilical cord and ductus venosus, which shunts well-oxygenated placental blood from the liver to the brain and heart. The low-risk group was selected to gain a better understanding of these factors in normal conditions rather than in extreme conditions in a high-risk group. Two independent effects were documented: the fetuses of women with low versus high central adiposity and operationally defined imprudent versus healthy diet had reduced ductus venosus shunting and increased liver blood flow. The observed fetal adaptations of cardiovascular responses to nutrient availability in this low-risk group suggested that these maternal characteristics were associated with liver-sparing response that “contrast with the brain-sparing response to fetal hypoxemia, which reduces hepatic flow and increases ductus venosus shunting” (p. 14). Harvey et al 13 reported on parental determinants of neonatal body composition in 448 births in the SWS, with dual-energy x-ray absorptiometry scan assessment of fat and muscle mass components of body composition in the offspring within 2 weeks of birth. With this rigorous measurement of neonatal body composition, this study documented that total fat mass was related to maternal lifestyle factors (smoking and physical activity) as well as maternal height, parity, and triceps skinfold thickness. One conclusion was that if these influences on fat mass have persisting effects, this information could point the way to early life interventions that may prevent later obesity. These examples of rigorous and prospective early evaluations in the SWS protocol show how modern methods can be used to assess fetal adaptations and their effects on structures and functions that may alter body composition (rather than just weight) at birth. This may provide improved estimates of the underlying DOHaD-related factors that contribute to risk for common adult disorders (e.g., obesity) later in life.

Collaboration between centers (see www.liggins.auckland.ac.nz/uoa/affiliations ) directed by the first two chairs of the DOHaD Society (Peter Gluckman from the Liggins Institute in Auckland and Mark Hanson from the MRC Epidemiology Resource Centre at the University of Southampton) led to the next generation of theory based on the concept of predictive adaptive response (see Gluckman and Hanson 14 ). Applications of the predictive adaptive response concept, presented and discussed in additional detail in a book by Gluckman and Hanson, 15 suggest that the fetus forecasts the future by sensing the current environment in utero and develops adaptively to match capabilities with expected demands. Gluckman et al 16 emphasized one of the premises of this hypothesis that the association of outcomes with birthweight is an epiphenomenon of the relationship between nutrient availability to the fetus and the predictive adaptive responses that this elicits. Gluckman et al 17 extended the concept of developmental plasticity by emphasizing that fetal programming may operate across the range from undernutrition to over-nutrition, with a U-shaped curve relating prenatal nutrition to adult metabolic disease.

Project VIVA: Background and Current Status

Gillman 18 noted limitations of undernutrition and low birthweight as markers of prenatal etiological pathways related to postnatal health outcomes. This led to consideration of fetal, infant, and child body composition as a phenotype and abnormalities anywhere in the maternal-fetal supply line of nutrients as a common final pathway that may alter body composition. Oken and Gillman 19 addressed the fetal origins of obesity and noted two different relationships with birthweight: a direct relationship held for birthweight with BMI in childhood and adulthood, but an inverse relationship held for low birth-weight with central adiposity, insulin resistance, and the metabolic syndrome. Gillman et al 20 , 21 used the life course approach to focus investigations on general in utero conditions and placental function and physiological processes regulating fetal development across a broad range of birth sizes, rather than on abnormal or pathological processes at one extreme.

Project VIVA was initiated in 1999 in eight offices of Harvard Vanguard Medical Associates, a large multi-specialty group practice in Massachusetts. Its initial goals were to identify women early in pregnancy and to enter them into a protocol for prospective assessments twice during pregnancy, within 3 days of birth, and at 6 months, and at 1, 2 and 3 years of age. 20 In 2006 it was extended to conduct follow-up through 7 years of age. The Web site for Project VIVA lists an impressive set of publications (see www.dacp.org/viva/publications.htm ), describing the initial evaluations of factors associated with blood pressure of the newborn, including maternal age 20 and maternal prenatal smoking, 22 and factors related to obesity at 3 years of age, including gestational weight gain 23 and weight in the first 6 months of life. 24 One example will be described in detail here that is particularly relevant to recent extensions of the DOHaD approach to consider more than birthweight as a predictor of early adaptations that are permanent and affect later outcomes by programming. Taveras et al 24 evaluated 559 children in Project VIVA to determine association of weight early in life (weight-for-length at birth and 6 months of age) with obesity (BMI >95th percentile) at 3 years of age. Weight early in life was directly associated with higher BMI at 3 years of age, but the association was larger for standardized weight at 3 years of age than for birth-weight. This suggest that increases in weight in the first 6 months of life may produce additional programming effects that increased risk for obesity in early childhood and thus may influence risk for later obesity more than birthweight alone that is assumed to reflect fetal programming.

Behavioral Perinatology Research Program: Background and Current Status

An early extension of the DOHaD approach was to go beyond nutrition hypotheses and to relate fetal development to exposure to other factors such as prenatal maternal stress and maternal-placental-fetal biological mediators of stress. Wadhwa 25 reviewed how psychoneuroendocrine processes in human pregnancy influence fetal development and health. Drake et al 26 reviewed the fetal glucocorticoid overexposure hypothesis as an alternative to the fetal undernutrition hypothesis to account for the relationship of the prenatal environment to adult disorders related to cardiovascular, metabolic, neuroendocrine, and behavioral phenotypes.

A multi-investigator research program at the University of California, Irvine, was initiated in 1993, and Wadhwa 25 reviewed the contributions of this program over the initial 12 years, which generated extensive information on the short-term effects of exposure to maternal psychosocial stress during pregnancy. This focused research documented that length of gestation and fetal growth are mediated, in part, by maternal-placental-fetal stress physiology, particularly placental corticotrophin-releasing hormone. Because simple birth phenotypes such as birthweight may represent a crude marker of intrauterine conditions that are likely to exert a causal role, this research program was recently extended based on the DOHaD approach to evaluate healthy young adults born with a normal birth-size phenotype (i.e., no low birthweight or preterm birth) but exposed during intrauterine life to maternal psychosocial stress, defined by a major stressful life event during pregnancy. Entringer et al 27 – 29 showed that compared with healthy young individuals without this history, these prenatal stress-exposed individuals exhibited primary insulin resistance and a lipid profile consistent with the metabolic syndrome, 27 altered immune function, 28 altered endocrine function, 29 and compromised cognitive function. 30 These findings suggest that in utero exposure to maternal stress may have long-term negative physiological consequences and may directly influence adult health even in the absence of adverse birth phenotypes such as low birthweight. Also directed by the DOHaD approach, Buss et al 31 evaluated brain morphology in young adults and revealed an association between birthweight and postnatal environment: Lower birth-weight was associated with smaller hippocampal volume (a well-established risk factor for depression and psychopathology) only in individuals exposed to postnatal adversity (low levels of parental bonding). Swanson and Wadhwa 32 have suggested that the DO-HaD approach also may be relevant to the origins of some child mental health disorders.

EPIGENETIC PROCESSES AND THE DOHaD APPOACH

In a review of the emerging science of epigenomics, Callinan and Feinberg 33 defined epigenetics as “the study of heritable changes other than those in the DNA sequence that encompass two major modifications of DNA or chromatin: DNA methylation, the covalent modification of cytosine, and post-translational modification of histones including methylation, acetylation, phosphorylation and sumoylation” (p. R95). They provide an excellent description of the potentially unique contributions of epigenetics, a glossary of terms, and a thorough description of methods used to detect genome-wide variation in DNA methylation and chromatin modification.

Outstanding reviews were published in 2007 that provide background on how the principles and concepts of epigenetics have been applied to the DOHaD approach. 34 – 36 If some of the mechanisms for developmental plasticity described in the DOHaD approach are epigenetic, and disease-related outcomes are related to disruptions of epigenetic processes elicited by the fetal environment, then this emerging field may provide explanatory mechanisms that underlie some of the enduring effects of adverse fetal, infant, and childhood environments. In their review of the DOHaD approach, Gluckman et al 17 provided an excellent summary of epigenetic modification of histones or of DNA itself in a figure (p. 66) that we reproduce here ( Fig. 1 ). This figure summarizes the important epigenetic processes of DNA methylation and histone acetylation and methylation that have been discussed and reviewed elsewhere 31 – 34 in detail and thus are not repeated here.

Regulation of gene expression through epigenetic processes. Epigenetic modification of histones or of DNA itself controls access of transcription factors (TFs) to the DNA sequence, thereby modulating the rate of transcription to messenger RNA (mRNA). Transcriptionally active chromatin (top) characterized by the presence of acetyl groups (Ac) on specific lysine residues of core histones in the nucleosome, which decreases their binding to DNA and results in a more open chromatin structure that permits access of transcription factors. In addition, cytidine-guanosine (CpG) sequences in the promoter regions (P) of actively transcribed genes are generally unmethylated, allowing for the binding of transcription factors. Transcriptionally inactive chromatin (bottom) is characterized by histone deacetylation, promoter CpG methylation (as indicated by methyl groups [Me]), and decreased binding of transcription factors. (For simplicity, other histone modifications [such as methylation] and additional regulatory factors [such as methyl-CpG binding proteins] are not shown.) A further level of epigenetic control is provided by microRNA molecules (19 to 22 nucleotides in length), which bind to complementary sequences in the 3′ end of mRNA and reduce the rate of protein synthesis. From Gluckman PD, Hanson MA, Cooper C, Thornburg KL. Effect of in utero and early-life conditions on adult health and disease. N Engl J Med 2008;359(1):61–73.

Two types of genes are modified epigenetically (i.e., are epigenetically liable): imprinted genes and genes with metastable epialleles. Imprinted genes are those in which specifically either the maternally derived or the paternally derived allele is suppressed, thereby rendering them functionally haploid (i.e., with parent-of-origin monoallelic expression). In other nonimprinted genes, one or both alleles are regulated epigenetically, and these metastable epialleles result in varying levels of gene expression. The modification of DNA from conception forward occurs to establish the epigenetic influence of gene expression, which is clearly presented in an article by Reik et al 37 that is often cited in reviews of imprinting. This article provided a figure outlining the processes of methylation reprogramming in the germ line and in preimplantation embryos that is reproduced here ( Fig. 2 ). As Leudi et al 38 discuss, many undiscovered genes are predicted to be imprinted, and this set of genes is likely to have special importance for reproductive medicine and fetal growth. They speculate about the evolutionary benefits of imprinted genes, which likely are the product of positive Darwinian selection despite potential drawbacks associated with a haploid gene compared with a diploid gene that has a backup copy that may protect from “single-hit” effects of DNA damage. Waterland and Michels 35 pointed out that in the DOHaD field “direct evidence of an involvement of epigenetic dysregulation in human cardiovascular disease, type 2 diabetes, and obesity is scant” compared with the field of cancer. They noted that this may be due to temporal and tissue specificity of the relevant tissue that may have epigenetic dysregulation associated diseases that have been the focus of the DOHaD approach, and they concluded that any disease with a genetic basis is also likely to have an epigenetic basis, but the “tissue-specificity of epigenetic regulation (and dysregulation) will be the major obstacle to epigenetic epidemiology of DOHaD” (p. 379). However, as pointed out by Gluckman and Hanson, 15 there is a strong epigenetic basis for the DOHaD model of disease pathogenesis based on animal studies, which (for example) show that minor alterations in the maternal diet during pregnancy can produce lasting changes in the physiology and metabolism of offspring. We summarize here classic findings from two research programs that have provided evidence about possible epigenetic mechanisms involved in this type of phenotypic plasticity in the DOHaD approach. More detailed description and review was provided as background for a 2006 meeting on Genes, Environments and Human Development, Health and Disease. 39

(A) Methylation reprogramming in the germ line. Primordial germ cells (PGCs) in the mouse become demethylated early in development. Remethylation begins in prospermatogonia on E16 in male germ cells and after birth in growing oocytes. Some stages of germ cell development are shown (modified from 73). (B) Methylation reprogramming in preimplantation embryos. The paternal genome (blue) is demethylated by an active mechanism immediately after fertilization. The maternal genome (red) is demethylated by a passive mechanism that depends on DNA replication. Both are remethylated around the time of implantation to different extents in embryonic (EM) and extraembryonic (EX) lineages. Methylated-imprinted genes and some repeat sequences (dashed line) do not become demethylated. Unmethylated imprinted genes (dashed line) do not become methylated. From Reik W, Dean W, Walter J. Epigenetic reprogramming in mammalian development. Science 2001;293(5532):1089–1093.

The Agouti Mouse Model

A group at Duke University has used a mouse model to investigate the effects of maternal diet during pregnancy on the phenotype manifested in the offspring ( www.geneimprint.com ). The viable yellow agouti (A vy ) mouse has a mutation that causes yellow hair pigmentation. A vy /a animals manifest a broad range of coat-color phenotypes from brown to mottled to yellow. Waterland and Jirtle 40 investigated methyl supplementation of the diet of mothers during pregnancy and showed when a standard diet is supplemented by methyl donors, methylation of the A vy gene increases and the coat-color distribution shifts toward the brown phenotype. Dolinoy et al 41 extended this work by investigation of effects of soy-rich diets before and during pregnancy in a/a females. The distribution of coat color in A vy offspring was shifted toward brown, and adult weight of the yellow phenotype was ~50% higher than in the brown phenotype. This demonstrated that for the A vy /a genotype of the viable yellow agouti mouse model, a high-soy diet results in epigenetic changes (increased methylation of CpG during fetal development), affects coat color, and also reduces obesity.

The Rat Model of Nurturing

A group at McGill University has used a rodent model to investigate epigenetic effects of maternal care. In rats, an important component of maternal care consists of licking and grooming, which varies widely across individuals. Meaney and Szyf 42 showed that increased licking and grooming increased hippocampal expression of the glucocorticoid receptor (GR) mRNA and protein, decreased hypothalamic corticotrophin-release factor, and reduced hypothalamic-pituitary-adrenal response to stress. This work showed a direct relationship between maternal behavior and DNA methylation in the rat hippocampal GR gene (specifically in the exon 1 7 promoter). Weaver et al 43 demonstrated further that the stress responses in adult rats that are programmed early in life by maternal care can be reversed by central infusion of methionine (a methyl donor), suggesting that the inherently stable epigenomic marks established by behavioral programming at a critical period early in life are potentially reversible later in life. This provides a biological basis for speculations about the effects of poverty on early experience, and how exposure to abuse, family strife, emotional neglect, and harsh discipline may have epigenetic effects that produce individual differences in neural and endocrine response to stress and may increase the susceptibility to common adult disorders such as depression and anxiety, drug abuse, and diabetes, heart disease, and obesity.

Recent Epigenetic Studies in Primates

Aaggard-Tillery et al 44 used a nonhuman primate model to investigate the effects of maternal diet on alternations to the epigenome that may be related to obesity. A high-fat diet (35% fat) was established that produced obesity in pregnant monkeys. In comparison with control animals with a control diet (13% fat), the offspring of the obese monkeys were obese. In the first stage of investigation, Aagaard-Tillery et al 44 identified an epigenetic change in the liver of these offspring (hyperacetylation of fetal hepatic tissue) that was associated with the high-fat diet and the resulting obesity. In the second stage, they altered the fat content of the monkeys’ diets during pregnancy. Even though obesity was maintained, the epigenetic changes in offspring were no longer present. This finding suggests that obesity may, in part, be due to the effects of maternal diet rather than maternal obesity on the fetal environment. This study in primates is important because it showed “ in utero exposure (caloric-dense high-fat maternal diet) induces site-specific alterations in fetal hepatic H3 acetylation” and that this leads “to epigenetically altered fetal chromatin structure in primates via covalent modifications of histones and hence lends a molecular basis to the fetal origins of adult disease hypothesis” (p. 91).

Tyckol 45 addressed the special nature of imprinted genes in placental growth. The placenta is the principal metabolic, respiratory, excretory, and endocrine organ of the fetus, which has substantial molecular variation across the fetal and maternal compartment (see Sood et al 46 ) and affects birthweight even after adjustment for placental weight (see Salafia et al 47 ). There are ~30 known imprinted genes, and a large percentage are expressed in trophoblasts and regulate placental growth. 48 In this review, placental phenotypes controlled by imprinted genes were discussed, as well as the role of oppositely imprinted genes (e.g., Igf2 and Igf2r) related to the evolutionary theory of genetic conflict described by Haig 49 that proposes different maternal and paternal self-interest in fetal growth. Some genes expressed in the placenta normally are maternally silenced/paternally expressed genes that promote growth (e.g., MEST) and others normally are maternally expressed/paternally silenced that limit growth (e.g., PHLDA2). In a study of intrauterine growth restriction (IUGR) and non-IUGR placenta, an altered expression of imprinted genes in placental response to maternal vascular underperfusion was investigated by McMinn et al. 50 In this study, IUGR was characterized by increased expression of PHLDA2 and decreased expression of MEST in placenta tissue. This suggested unbalanced expression of these two oppositely imprinted genes was one component of the adaptive response of placental tissue to chronic maternal vascular underperfusion associated with IUGR, which provides some support for the conflict hypothesis. New methods are emerging for assessing epigenetic marks, such as the MSNP approach for determining allele-specific methylation and allele-specific expression patterns that may be dependent or independent of genome sequence (see Kerkel et al 51 ). In the study of IUGR, there was no evidence of altered DNA methylation in imprinting centers of the PHLDA2 and MEST genes, which led McNinn et al 50 to conclude that “the high PHLDA2/MEST mRNA ratios in this subset of IUGR may reflect altered DNA methylation in as yet uncharacterized cis -acting regulatory sequences, but more likely reflects conventional transcriptional dysregulation by trans acting factors in placental cytotrophoblasts” (p. 543).

RELEVANCE OF EPIGENETIC AND THE DOHaD HYPOTHESIS TO REPRODUCTIVE MEDICINE

Niemtz and Feinberg 52 provide an example of early epigenetic research in reproductive medicine. 52 They investigated a possible a link between assisted reproductive therapy (ART) and Beckwith-Wiedemann syndrome (BWS). 53 This syndrome is characterized by genetic heterogeneity, but about half the cases are associated with loss of imprinting in genes related to growth (e.g., the LIT1 gene located on the tip of chromosome 11). Niemitz and Feinberg 52 suggested that “epigenetic alterations could arise from some aspect of ART” (e.g., in the in vitro culture itself or the media used) or that “epigenetic alteration could be a significant cause for infertility, rather than a consequence of the procedures used to treat it” (p. 605). Chang et al 54 tested that hypothesis that culture media would be implicated as a common factor among children with BWS conceived after ART, but in a small sample of 19 they reported that in vitro fertilization (IVF) was a common factor but otherwise “no common factor was identified among reproductive endocrine records,” and they concluded “larger prospective studies are needed to systematically assess the potential risk factors associated with BWS and ART” (p. 353).

A summary of recent studies relevant to reproductive medicine is facilitated by two recent reviews in the series of Seminars in Reproductive Medicine, 55 , 56 which provide detailed background for the application of the DOHaD approach to reproductive medicine and epigenetic processes ( Fig. 1 ) that may operate at the time of conception ( Fig. 2 ).

Rinaudo and Lamb 55 summarized the literature on in utero stress related to deficient maternal-placental nutrient supply and some adverse childhood and adult outcomes (i.e., cardiovascular disease, hypertension, diabetes, and dysregulation of the hypothalamic-pituitary-adrenal axis) associated with stressful fetal environments during the postimplantation period of fetal growth. They also provided a brief review of perinatal morbidity associated with stress during the preimplantation period related to in vitro culture in assisted reproduction. They concluded that the evidence linking stress in utero to risk for adult disorders is convincing, and that the preimplantation embryo development is particularly sensitive to epigenetic regulation and dysregulation.

Kalra and Molinaro 56 summarized the literature on association of in vitro fertilization with perinatal morbidity and the risk for congenital abnormalities, preterm birth, low birthweight, and other pregnancy-related complications. They concluded that children “conceived after IVF do seem to be at an increased risk for congenital and chromosomal anomalies compared with that of natural conceptions, particularly if ICSI [intracytoplasmic sperm injection] is used” (p. 432), but that effects have not yet been determined for long-term outcomes related to the DOHaD approach and physical, emotional, or cognitive development.

Other reviews of reproductive outcomes after IVF 57 and ICSI 58 also are available and add to the growing recognition that alteration of biochemical and biophysical conditions at conception and during early embryonic life associated with ARTs may result in changes in epigenetic processes and produce short- and long-term effects on development and health.

NEXT STEPS: LARGE HUMAN COHORT STUDIES

There are many recent developments in the field of epigenetics. The NIH Roadmap program on the Epigenomics of Human Health and Disease ( www.nih.gov ) was initiated to accelerate new developments, including the characterization of reference epigenomes in non-disease states and the perturbation of these epigenomes in disease states that may be temporally and tissue specific. Recent workshops (Epigenomics of Addiction) and conferences (Epigenomics of Human Health and Disease) have summarized these new developments in the understanding of mechanisms and methods that are being applied in the current investigations. The basic processes that describe how cells with the same molecular instructions (the DNA code) become differentiated during development through differential expression of genes have been reviewed in detail, with information available on the NIH Web site (see www.nida.nih.gov ).

The next phase of research to address epigenetic mechanisms in humans would benefit substantially from large birth cohort studies with prospective measures of broad domains of exposures and outcomes. 35 , 59 There are good examples in the literature. Recently, the Avon Longitudinal Study of Parents and Children (ALSPAC) study, 60 the Danish National Birth Cohort, 61 and the SWS 11 have taken initial steps to identify critical developmental processes that underlie fetal growth and development 13 , 62 , 63 and later outcomes in childhood related to the overnutrition hypothesis, 64 preterm birth, 61 and body composition. 13

A prospective birth cohort, the National Children’s Study (NCS), is now underway in the United States. The NCS will recruit a nationally representative birth cohort at 105 sites with ~100,000 children. The recruitment will start with randomly designated neighborhoods and a survey of households within them to identify ~750,000 women between the 18 and 40 years of age who are not pregnant or within the first trimester of pregnancy. These women will be evaluated and followed until ~1000 births occur at each of the 105 locations (for an expected total of ~105,000). Broad exposures and outcome domains will be assessed at multiple times across stages of development (before conception, during pregnancy, and at birth; in infancy, childhood, adolescence; and into adulthood). A recent summary of the background, controversies, and status of the NCS was provided by Landrigan et al. 65 The NCS will provide a prospective evaluation of a large birth cohort with early and frequent direct observation of the same individuals over time, which will provide rich information about health and disease that will be stored in clinical databases as well as biological and environmental samples that will be stored in biospecimen repositories. This information will be used initially to evaluate 29 “priority” hypotheses that were developed during the early consensus-development phase of the project in 2002 and then updated by the Vanguard Centers of the NCS in 2007 (see www.nationalchildrensstudy.gov ). However, with such a large and representative birth cohort characterized by broad exposure and outcome domains, many more hypotheses will be tested and will emerge as the NCS progresses.

Although the NCS does not provide specific funding for genetic or epigenetic analyses, it does have a goal to provide the NCS clinical databases and biospecimen repositories for use in approved and separately funded adjunct studies designed to take advantage of the extensive infrastructure of the NCS. Swanson and Wadhwa 32 presented and discussed three critical issues that highlight the extraordinary value of the birth cohort design used by the NCS, and here we note some significant issues and problems associated with each one:

• If the nature of the combined effect of multiple genetic and environmental risk factors on complex common disorders is nonadditive, as assumed by the DOHaD approach, then the best way to elucidate these interactive effects is to assess the various risk factors simultaneously in the same cohort rather than in separate cohorts as proposed by Willet et al. 66 However, the cost and subject burden required to conduct a birth cohort study are limiting factors that are now being considered in the NCS. 67
• If vulnerability to a particular risk factor or disease phenotype is determined not only by the genome acquired at conception but by the nature of its interplay with the environments during successive critical periods of development, a key feature of the DOHaD approach, then a longitudinal assessment of the environment from before conception through pregnancy, fetal life, birth, and infancy may be necessary, instead of relying on assessment of the environment in adult life as proposed by Collins and Manolio, 68 to better understand disease susceptibilities that may have fetal or developmental origins. However, the investment in time, the retention of the sample, and the continuity of funding are issues that are facing the NCS. 69
• If the interplay between genes and environment is characterized by dynamic modifications to the genome, as assumed by the DOHaD approach, then not only the stable DNA sequence but also the epigenetic modifications to nuclear DNA and chromatin structure must be investigated serially during critical periods in early development over time and under various environmental conditions to assess gene–environment interactions adequately. However, the issues of temporal and tissue specificity must be addressed. 35 The need for multiple collections of environmental exposures and biological specimens and the limitation inherent in human studies of the availability of many specific tissue types create truly daunting tasks that must be addressed before the full study can be initiated. 70 The Vanguard Centers (7 of the 105 locations) are now conducting a field test of the NCS draft protocol that is intended to provide an empirical basis for decisions about feasibility and costs, which will be used to establish the final protocol for implementation in all 105 locations. 71

The NCS provides an extraordinary opportunity to develop genetic and epigenetic projects and make use of the DOHaD approach to address specific mechanisms related to common disorders (e.g., obesity 72 ) that are increasing by epidemic proportions around the world and define critical issues for consideration in the area of reproductive medicine.

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Understanding Developmental Psychology

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Daniel B. Block, MD, is an award-winning, board-certified psychiatrist who operates a private practice in Pennsylvania.

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Frequently Asked Questions

Change is inevitable. As humans, we constantly grow throughout our lifespans, from conception to death. The field of developmental psychology explores the behavioral, emotional, physical, and cognitive changes that happen as people age.

Psychologists strive to understand and explain how and why people change throughout life. While many of these changes are normal and expected, they can still pose challenges that people sometimes need extra assistance to manage.

The principles of normative development help professionals spot potential problems and provide early intervention for better outcomes. Developmental psychologists can work with people of all ages to address roadblocks and support growth, although some choose to specialize in a specific age group such as childhood, adulthood, or old age.

What Is Developmental Psychology?

Developmental psychology is the branch of psychology that focuses on how people grow and change over the course of a lifetime.

Those who specialize in this field are not just concerned with the physical changes that occur as people grow; they also look at the social, emotional, and cognitive development that occurs throughout life.

Some of the many issues developmental psychologists assist with include:

• Cognitive development during childhood and throughout life
• Developmental challenges and learning disabilities
• Emotional development
• Language acquisition
• Moral reasoning
• Motor skill development
• Personality development
• Self-awareness and self-concept
• Social and cultural influences on child development

These professionals spend a great deal of time investigating and observing how these processes occur under normal circumstances, but they are also interested in learning about things that can disrupt developmental processes.

By better understanding how and why people change and grow, developmental psychologists help people live up to their full potential. Understanding the course of normal human development and recognizing potential problems early on can prevent difficulties with depression, low self-esteem, frustration, and low achievement in school.

Developmental Psychology Theories

Developmental psychologists often utilize a number of theories to think about different aspects of human development. For example, a psychologist assessing intellectual development in a child might consider Piaget's theory of cognitive development , which outlined the key stages that children go through as they learn.

A psychologist working with a child might also want to consider how the child's relationships with caregivers influences his or her behaviors, and so turn to Bowlby's theory of attachment .

Psychologists are also interested in looking at how social relationships influence the development of both children and adults. Erikson's theory of psychosocial development and Vygotsky's theory of sociocultural development are two popular theoretical frameworks that address the social influences on the developmental process.

Each approach tends to stress different aspects of development such as mental, social, or parental influences on how children grow and progress .

When to See a Developmental Psychologist

While development tends to follow a fairly predictable pattern, there are times when things might go off course. Parents often focus on what are known as developmental milestones, which represent abilities that most children tend to display by a certain point in development. These typically focus on one of four different areas:

• Physical milestones
• Cognitive milestones
• Social/emotional milestones
• Communication milestones

For example, walking is one physical milestone that most children achieve sometime between the ages of 9 and 15 months. If a child is not walking or attempting to walk by 16 to 18 months, parents might consider consulting with their family physician to determine if a developmental issue might be present.

While all children develop at different rates, when a child fails to meet certain milestones by a certain age, there may be cause for concern.

By being aware of these milestones, parents can seek assistance, and healthcare professionals can offer interventions that can help kids overcome developmental delays.

These professionals often evaluate children to determine if a developmental delay might be present, or they might work with elderly patients who are facing health concerns associated with old age such as cognitive declines, physical struggles, emotional difficulties, or degenerative brain disorders.

Developmental psychologists can provide support to individuals at all points of life who may be facing developmental issues or problems related to aging.

Developmental Psychology Stages

As you might imagine, developmental psychologists often break down development according to various phases of life. Each of these periods of development represents a time when different milestones are typically achieved.

People may face particular challenges at each point, and developmental psychologists can often help people who might be struggling with problems to get back on track.

Prenatal Development

The prenatal period is of interest to developmental psychologists who seek to understand how the earliest influences on development can impact later growth during childhood. Psychologists may look at how primary reflexes emerge before birth, how fetuses respond to stimuli in the womb, and the sensations and perceptions that fetuses are capable of detecting prior to birth.

Developmental psychologists may also look at potential problems such as Down syndrome, maternal drug use, and inherited diseases that might have an impact on the course of future development.

Early Childhood Development

The period from infancy through early childhood is a time of remarkable growth and change. Developmental psychologists look at things such as the physical, cognitive, and emotional growth that takes place during this critical period of development.

In addition to providing interventions for potential developmental problems at this point, psychologists are also focused on helping kids achieve their full potential . Parents and healthcare experts are often on the lookout to ensure that kids are growing properly, receiving adequate nutrition, and achieving cognitive milestones appropriate for their age.

Middle Childhood Development

This period of development is marked by both physical maturation and the increased importance of social influences as children make their way through elementary school.

Kids begin to make their mark on the world as they form friendships, gain competency through schoolwork, and continue to build their unique sense of self. Parents may seek the assistance of a developmental psychologist to help kids deal with potential problems that might arise at this age including social, emotional, and mental health issues.

Adolescent Development

The teenage years are often the subject of considerable interest as children experience the psychological turmoil and transition that often accompanies this period of development. Psychologists such as Erik Erikson were especially interested in looking at how navigating this period leads to identity formation .

At this age, kids often test limits and explore new identities as they explore the question of who they are and who they want to be. Developmental psychologists can help support teens as they deal with some of the challenging issues unique to the adolescent period including puberty, emotional turmoil, and social pressure.

Early Adult Development

This period of life is often marked by forming and maintaining relationships. Critical milestones during early adulthood may include forming bonds, intimacy, close friendships, and starting a family.

Those who can build and sustain such relationships tend to experience connectedness and social support while those who struggle with such relationships may be left feeling alienated and lonely .

People facing such issues might seek the assistance of a developmental psychologist in order to build healthier relationships and combat emotional difficulties.

Middle Adult Development

This stage of life tends to center on developing a sense of purpose and contributing to society. Erikson described this as the conflict between generativity and stagnation .

Those who engage in the world, contribute things that will outlast them, and leave a mark on the next generation emerge with a sense of purpose. Activities such as careers, families, group memberships, and community involvement are all things that can contribute to this feeling of generativity.

Older Adult Development

The senior years are often viewed as a period of poor health, yet many older adults are capable of remaining active and busy well into their 80s and 90s. Increased health concerns mark this period of development, and some individuals may experience mental declines related to dementia.

Theorist Erik Erikson also viewed the elder years as a time of reflection back on life . Those who are able to look back and see a life well-lived emerge with a sense of wisdom and readiness to face the end of their lives, while those who look back with regret may be left with feelings of bitterness and despair.

Developmental psychologists may work with elderly patients to help them cope with issues related to the aging process.

Diagnosing Developmental Issues

To determine if a developmental problem is present, a psychologist or other highly trained professional may administer either a developmental screening or evaluation.

For children, such an evaluation typically involves interviews with parents and other caregivers to learn about behaviors they may have observed, a review of a child's medical history, and standardized testing to measure functioning in terms of communication, social/emotional skills, physical/motor development, and cognitive skills.

If a problem is found to be present, the patient may then be referred to a specialist such as a speech-language pathologist, physical therapist, or occupational therapist.

A Word From Verywell

Receiving a diagnosis of a developmental issue can often feel both confusing and frightening, particularly when it is your child who is affected. Once you or your loved one has received a diagnosis of a developmental issue, spend some time learning as much as you can about the diagnosis and available treatments.

Prepare a list of questions and concerns you may have and discuss these issues with your doctor, developmental psychologist, and other healthcare professionals who may be part of the treatment team. By taking an active role in the process, you will feel better informed and equipped to tackle the next steps in the treatment process.

The three major developmental psychology issues are focused on physical development, cognitive development, and emotional development.

The seven major stages of development are:

• Infant development
• Toddler development
• Preschool development
• Middle childhood development
• Adolescent development
• Early adult development
• Older adult development

The principles of developmental psychology outlined by Paul Baltes suggest that development is (1) lifelong, (2) multidimensional, (3) multidirectional, (4) involves gains and losses, (5) plastic, and that developmental psychology is (6) multidisciplinary.  

Four developmental issues that psychologists explore are focused on the relative contributions of:

• Nature vs. nurture : Is development primarily influenced by genetics or environmental factors?
• Early vs. later experience : Do early childhood events matter more than events that happen later in life?
• Continuity vs discontinuity : Is developmental change a gradual process or do changes happen suddenly and follow a specific course?
• Abnormal behavior vs. individual differences : What represents abnormal development and what can be considered individual variations in development?

Keenan T, Evans S. An Introduction to Child Development . 2nd ed. SAGE; 2009.

• Erikson EH. (1963).Childhood and Society. (2nd ed.). New York: Norton.
• Erikson EH. (1968).Identity: Youth and Crisis. New York: Norton.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

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Genetic hypothesis for the developmental origins of health and disease theory

Zhao, Xinzhi ∗

a International Peace Maternity & Child Health Hospital of China Affiliated to Shanghai Jiao Tong University

b Shanghai Key Laboratory of Embryo Original Diseases, Shanghai, China.

∗Corresponding author: Xinzhi Zhao, International Peace Maternity & Child Health Hospital of China Affiliated to Shanghai Jiao Tong University, Shanghai 200030, China. E-mail: [email protected] .

This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0

The developmental origins of health and disease theory states that environmental stresses during the early stages of life influence health and risk of developing non-communicable diseases throughout the lifespan of an individual. Developmental plasticity is thought to be a possible underlying mechanism. Here, I discuss a contrasting but complementary genetic hypothesis regarding the developmental origins of health and disease theory: crosstalk between the genomes of the parents and offspring is responsible for shaping and adapting responses to environmental stresses, regulating early growth and predisposition to non-communicable diseases. Genetic variants that are beneficial in terms of responses to early life stresses may have pleiotropic detrimental effects on health later in life, which may change the allele frequencies driven by selection on a population level. Genetic studies on the cohort of children born after assisted reproduction could provide insight regarding the genetic mechanisms of the developmental origins of health and disease theory.

Introduction

Non-communicable diseases (NCDs), also known as chronic diseases, are characterized by slow progression and long duration. Prominent NCDs include cancer, cardiovascular diseases, diabetes mellitus, and major psychiatric diseases. Over the past two centuries, dramatic improvements in healthcare have increased the global life expectancy and changed the patterns of disease. NCDs account for a substantial proportion of the global disease burden and are currently responsible for over 63% of the world's deaths. [1]

The etiologies of NCDs are generally complex and consist of multiple genetic and environmental factors. The discovery that disorders of intrauterine development were associated with risk of NCDs in adult life was an important finding of the late 20th century. David Baker and colleagues reported an increased rate of death from ischemic heart disease in individuals with low birth weight in an English cohort, [2] and later this association was replicated in several different populations. [3,4] Low birth weight was also found to be associated with disorders characterized by insulin resistance, such as type 2 diabetes (T2D), hypertension, and dyslipidaemia. [5] Based on these observations, Barker formulated the hypothesis of the developmental origins of health and disease (DOHaD), which proposes that exposure to environmental factors during specific sensitive periods of development might predispose an organism to diseases in adult life. [6] An increasing number of studies have connected exposure to stresses during early life after conception, or even during preconceptional gametogenesis, with increased risks for chronic conditions.

Although the association has been well established by many epidemiology studies, the underlying mechanisms of the DOHaD theory are not fully understood. Some important hypotheses are based on developmental plasticity. [7] Many organisms have been found to express adaptive responses to their environments and to form specific characteristics. However, if the environment changes, these characteristics could result in maladaptation, and could increase the risk of contracting disease. Hales and Baker [8] put forward the thrifty phenotype hypothesis to explain the associations between poor fetal and infant growth and an increased risk of developing impaired glucose tolerance or metabolic syndrome in adult life. The hypothesis states that poor nutrition in fetal and early infant life induces specific programming of development and function of pancreatic β-cells, as well as kidney, muscle, liver, vascular, hypothalamic-pituitary-adrenal axis, and sympathetic systems. The programming leads to a thrifty phenotype with reduced fetal growth and poor organic function. These individuals would be well adapted to living in a continuously poorly nourished state, but would be maladapted to overnutrition in adult life, putting them at risk of developing a metabolic syndrome.

An alternative explanation to the DOHaD theory is genetic pleiotropy, the phenomenon in genetics whereby a DNA variant influences multiple traits. Given the limited number of genes in the human genome, and the enormous dimensionality of the phenome, it is reasonable to expect that many functional variants have pleiotropic effects. [9] Those genetic variants that affect development and influence adaptive responses to environmental stresses at an early age may also contribute to the genetic risk of NCD later on in life. The association between changes early in development and the onset of NCDs later in life may be a coupled phenomenon caused by a common mechanism.

In this review, I focus on the following potential genetic factors in the DOHaD theory, 1) the genetic variants linking early life development, mainly during intrauterine growth, and the risk of NCDs, 2) possible antagonistic pleiotropy and positive/negative selection for these genetic variants, and 3) the interaction between genetic and environmental factors. I also discuss how the growing population of individuals born as a result of assisted reproduction provides a unique opportunity to investigate the genetic mechanisms of DOHaD theory.

Database search strategy

In this review, the author performed a search for original and review articles published in English between January 1989 and June 2019 focusing on genetic hypothesis of DOHaD theory in PubMed database. The following search terms were used alone or in combination: “genetics in developmental origins of health and disease”, “genetic pleiotropy”, “genetics of intrauterine growth”, “genetics of birth weight”, “positive selection”, “assisted reproduction”. The bibliographies of pertinent articles were also examined to identify further relevant papers.

The “thrifty genotype” hypothesis

As early as 1962, the American geneticist James Neel [10] put forth the “thrifty genotype” hypothesis. He proposed that genetic variants that reduce glucose uptake and limit body growth facilitated survival during periods of famine, and therefore these thrifty alleles would be positively selected in preindustrialized societies, in which famine is frequent. When individuals who have the thrifty genotype encounter a modern industrialized environment with plentiful food/low energy expenditure, they are at risk of developing metabolic syndromes. This hypothesis was initially used to explain the increasing prevalence of T2D among many indigenous populations, and was modified in the following years in conjunction with new information regarding the complexity of metabolic disease. [11]

The thrifty genotype hypothesis was applied to the mechanism of DOHaD by Hattersley and Tooke. [12] They proposed the fetal insulin hypothesis, which states that genetic factors are important both as determinants of birth weight and in evaluating the risk of adult metabolic syndromes. In other words, they proposed that the “thrifty phenotype” is the result of a “thrifty genotype”. Insulin pathways are considered to be excellent candidates for a common link because insulin plays a key role in both metabolism syndrome and fetal growth.

The thrifty genotype hypothesis employed an evolutionary framework to explain the growing burden of NCDs in contemporary populations. Nevertheless, many critiques of the hypothesis [13] arose due to the general lack of genetic evidence until recently. However, in the past 15 years, high throughput genomic platforms have generated huge amounts of genetic data enabling numerous genome-wide association studies (GWAS). A number of genetic variants that increase NCDs risk in old age have been found to be associated with increases in survival, fertility or lifetime reproductive success (LRS).

The genetic variants linking early development and adult diseases

Low birth weight has been identified as an important risk factor for many NCDs, and the association is primarily the result of growth retardation, rather than preterm birth. [14] Birth weight is a complex multifactorial trait, and genetic factors play an important role that is independent of the intra-uterine environment. [15] This trait is extremely polygenic, and is controlled by large numbers of loci of small effect. As a result, it is quite difficult to identify the genetic loci that influence birth weight. Fortunately, birth weight is an easy-accessible demographic trait. Meta-analyses of GWAS data from multiple large-scale studies have yielded sufficient power to detect the genetic variants associated with birth weight, and many loci have been identified. A complex correlation between birth weight and adult disease risk has been demonstrated.

Using the GWAS data from a cohort of 5465 Caucasian children with recorded birth weights, Zhao et al [16] investigated the association between birth weight and previously reported T2D-associated variations at 20 loci. They found that the minor allele of a single nucleotide polymorphisms (SNPs) rs7756992 at the CDKAL1 locus was associated with lower birth weight, although the association did not reach genome-wide significance. [16] Later, this finding was replicated in a Danish cohort consisting of 4744 individuals. [17] The researchers also reported that birth weight was inversely associated with the T2D risk alleles of rs11708067 in ADCY5 . Freathy et al [18] searched for common genetic variants associated with birth weight in 38,214 individuals of European descent. They identified that rs900400, located near CCNL1 , and rs9883204, located in ADCY5 , were robustly associated with birth weight. The SNP rs9883204 showed a relatively strong linkage disequilibrium with rs11708067, which implied that it is involved in the regulation of glucose levels and thus T2D susceptibility. [19] The inverse genetic correlations between birth weight and T2D at the ADCY5 and CDKAL1 loci were confirmed in an expanded GWAS (with 69,308 individuals of European descent). [20] These results provided direct support for the fetal insulin hypothesis. [12]

The birth weight loci are not all associated with NCDs. For example, rs900400, which is located near the CCNL1 locus, is not known to be associated with any other traits. [20] Moreover, some alleles associated with higher birth weight may confer risk of NCDs. rs1801253 in ADRB1 has been strongly associated with birth weight, as well as systolic and diastolic blood pressure. [19,21] However, the birth weight-lowering allele at rs1801253 is associated with lower blood pressure in later life. [20] Importantly, birth weight may be influenced by both fetal and maternal genotype, and through the cellular mechanisms of gametogenesis and fertilization, fetal genotype is correlated with maternal genotype ( r ≈ 0.5). In some cases, functional alleles may exert different effects on birth weight depending on whether they are carried by the mother or fetus. For instance, rare heterozygous mutations in the glucokinase gene of a fetus may result in a reduction of approximately 530 g in birth weight, while mothers who carry a glucokinase mutation may have offspring that weigh 600 g more than average due to maternal hyperglycemia. [22]

In a recent multi-ancestry GWAS meta-analysis of birth weight in 153,781 individuals, [23] the authors identified 7 previously reported and 53 novel loci that were associated with birth weight at a genome-wide significance level for populations with either European ancestry or trans-ancestry. Further, three of the loci harbored multiple distinct association signals attaining genome-wide significance. The lead SNPs in these loci were almost common variants and they individually had modest effects on birth weight (10–26 g per allele). Using a linkage disequilibrium score regression method for the data from samples with European ancestry, the researchers found that birth weight was inversely correlated with genetic indicators of adverse metabolic and cardiovascular health, reflecting the impact of shared genetic variants that influence both sets of phenotypes. However, they also observed locus-specific heterogeneity in the genetic relationships between birth weight and health-related traits, including the replication of rs1801253 in ADRB1 that the birth weight-lowing allele is associated with lower blood pressure. [20] Meanwhile, the researchers found that both maternal and fetal genetic effects connect birth weight to later T2D risk, albeit acting in opposing directions, by analyzing the loci associated with both traits in mother-child pairs.

These studies provide compelling evidence that fetal genotype plays an important role in early growth, as measured by birth weight. Further, the loci that impact birth weight may contribute to the adult risk of metabolic diseases, providing some support for the idea of the “thrifty genotype”. However, these findings can only explain a small part of the variance in birth weight, and the effect of any individual loci is very small. For example, 62 distinct and significant genome-wide signals that were identified in more than 150,000 individuals account for approximately 2% of the variance. [23] Moreover, the genetic correlation between birth weight and other adult health-related traits is complex, and is likely to be indirectly influenced by the maternal genome.

Positive selection for the risk alleles of susceptibility to NCDs

While NCDs have very clear negative impacts, they also have a large genetic component. The cost to fitness for the individuals carrying risk alleles of susceptibility to NCDs may be relatively small because they would have transmitted the alleles to the next generation before the onset of age-related NCDs. A key point of the “thrifty genotype” hypothesis is that the risk alleles of susceptibility to NCDs may confer advantages during early life in a severe environment, and therefore contribute to a net fitness benefit. These risk alleles may even be positively selected. Natural selection is the principal underlying force molding life via traits associated with survival and reproduction. [24] Therefore, it is possible that the thrifty genes may contribute to sustaining fecundity besides survival during famine, as mentioned by Prentice. [25]

Considering that the quantitative traits associated with early development and NCSs are extremely polygenic, positive selection of the loci may occur via polygenic adaptation, and the selection signals may go largely undetected by conventional methods. [26] An allele that is positively selected may rise in prevalence rapidly such that recombination does not substantially break down the association with alleles at nearby loci on the ancestral chromosome, and so a long haplotype is formed. Based on this theory, an integrated Haplotype Score method has been developed to estimate positive selection for genetic polymophisms. [27] This method is typically used to detect candidate adaptive SNPs where the selected alleles may not have reached fixation, as it is well suited for detecting recent selection signals. Another haplotype-based method for computing nS L scores (the number of segregation sites by length) is more robust than the integrated Haplotype Score and does not depend on a genetic map. [28] Most selected regions have been found to be limited to a specific population, [27] suggesting adaption to local environments. Moreover, LRS, the number of children per parent per lifetime, is a prerequisite for responses to selection, and provides a measure of fitness that combines survival and reproduction.

Although several early studies failed to detect the selection signatures in metabolic genes, [29,30] compelling evidence was found in a Samoan population. Samoan people represent a unique founder population with a high prevalence of obesity. A recent GWAS identified a functional variant, rs373863828, with a large effect size (p.Arg457Gln, meta P = 1.4 × 10 −20 , 1.36–1.45 kg/m 2 per copy of the risk allele) in CREBRF that strongly influences body mass index in Samoan population. [31] Interestingly, while the variant is common in Samoan people, it is extremely rare in other populations. The body mass index-raising allele of rs373863828 showed decreased energy use and increased fat storage in an adipocyte cell model, and therefore was considered to be a thrifty variant. Positive selection of this thrifty variant was observed according to the integrated Haplotype Score and nSL score.

The positive selection of risk alleles associated with NCDs is not limited to obesity or specific populations. Evidence of positive selection was found in 40 of the 76 genes known to be associated with the risk of coronary artery disease in a GWAS of 12 human populations. [32] The coronary artery disease genes under positive selection were enriched in a number of traits associated with reproduction and pregnancy outcomes, including twinning, reproductive timing, lactation capacity, pregnancy loss, intrauterine growth restriction (IUGR), and preeclampsia. Meanwhile, the authors found antagonistic relationships between coronary artery disease and reproductive success in women in the Framingham Heart Study.

Human reproductive behavior including age at first birth and the number of children ever born (same as LRS) is strongly related to fitness. A GWAS that combined genome data from more than 300,000 individuals identified 12 independent loci that were significantly associated with age at first birth and/or number of children ever born. [33] Genetic correlation estimates found that the alleles linked to lower age at first birth in both men and women were associated with a higher genetic risk of smoking and T2D, while the number of children ever born was negatively genetically correlated with years of education and age at first sexual intercourse. No significantly enriched genes, tissue sets, or biological functions were found to be enriched for the genes associated with reproductive behavior. These results indicate that human reproductive behavior is influenced by a mixture of biological, psychological, and socio-environmental factors in contemporary populations.

Although limited in number, some reliable studies have identified specific genes associated with the risk of NCDs that are under positive selection, and may contribute to LRS. The positive signals of selection or association with LRS are generally very weak for a single locus. Large databases that contain information on genomics, fertility, mortality, and health status from hundreds of thousands of individuals are required to identify these genes.

Antagonistic pleiotropy in the maternal and fetal genome

Recent studies have suggested a substantial role of genetics in the association between early development and adult NCDs. However, the effect sizes of the candidate loci are so small that they can only be identified in very large cohort studies, and some locus-specific heterogeneity has also been observed. As mentioned above, the quantitative traits related to early development and NCDs are extremely polygenic and have complex gene-environment interactions. Moreover, evidence of substantial crosstalk between the genomes of parents and offspring has been observed during pre-implantation and development. Here, as an example of how crosstalk between the mother and fetus shapes the intrauterine growth environment and impacts early development, I describe the antagonistic responses between the mother and fetus during adaptation to defective deep placentation.

Human pregnancy is characterized by deep placentation, in which placental trophoblasts invade up to a depth of one-third of the thickness of the myometrium. This process is accompanied by transformation of the uterine spiral arteries from a low-velocity to a high-flow chamber. Transformation of the spiral arteries facilitates increases in uterine blood flow to enable perfusion of the intervillous space of the placenta and support fetal growth. Defective deep placentation, which is defined as a significantly increased number of spiral arteries with absent or partial transformation, results in placental ischemia, and is associated with a spectrum of obstetric disorders including preeclampsia, IUGR, preterm labor, preterm premature rupture of membranes, late spontaneous abortion, and abruptio placentae. [34]

Clinical outcomes of defective deep placentation are determined by two major factors. The first is the degree to which physiological transformation of the spiral arteries is restricted. For example, 90% of the myometrial spiral arteries are fully transformed in normal pregnancy. However, in cases of severe early-onset preeclampsia, which is a pregnancy-induced hypertension syndrome associated with IUGR, only a few spiral arteries may be fully transformed. In late-onset preeclampsia (LOPE) without IUGR, IUGR without hypertension, and preterm labor, defective deep placentation may only partially affect the spiral arteries. [34] The trophoblast invasion plays a key role in the transformation of the spiral arteries. Importantly, the placenta is genetically identical to the fetus, and is semi-allogeneic to the mother. Thus, the trophoblast invasion challenges the maternal immune system. [35] Complete failure of immunoregulatory mechanisms could lead to spontaneous abortion, whereas partial failure could lead to a continued pregnancy with a small, insufficient placenta. Thus, there exists a continuum between abortion, pre-eclampsia, and other disorders associated with deep placentation. HLA-C expressed by trophoblasts can be recognized by decidual killer immunoglobulin-like receptors, in a process involved in maternal-fetal tolerance. Combinations in which the mother carries two killer immunoglobulin-like receptor AA haplotypes and the fetus inherits paternal HLA-C2 haplotypes are the most susceptible to preeclampsia and recurrent miscarriages. [36]

A second factor in determining the clinical outcome in cases of defective deep placentation is the maternal and fetal adaptive responses to the compromised placental blood supply. Unlike diseases in the non-pregnant state, obstetric disorders develop in a unique biological situation in which a mother and fetus with different genomes coexist. [37] Compromised placental blood supply restricts the transportation of oxygen and nutrients, which can lead to ischemia–reperfusion injury and retarded fetal growth. Meanwhile, a series of adaptive responses may occur in placental trophoblast cells: hypoxia-inducible factors may increase as a response to cellular oxygen deprivation; antiangiogenic factors including soluble vascular endothelial growth factor receptor1 (sVEGFR-1) and soluble endoglin may be up-regulated; endoplasmic reticulum stress induced by ischemia–reperfusion injury may suspend protein folding, leading to trophoblast apoptosis; and the production of reactive oxygen species may increase, inducing the release of proinflammatory cytokines and chemokines, as well as trophoblast debris. These placental responses release soluble components into the maternal circulatory system and may trigger a non-specific, systemic (vascular), inflammatory response leading to clinical symptoms in the mother. [38]

Among clinical measures of maternal health status, hypertension may be the most important because it can reflect an important fetal adaptive response – increased placental perfusion. In a meta-analysis examining the relationship between fetoplacental growth and the use of oral antihypertensive medication to treat mild-to-moderate hypertension during pregnancy in 45 randomized controlled trials, treatment-induced decreases in maternal blood pressure appeared to adversely affect fetal growth. Specifically, greater decreases in mean arterial pressure from study enrolment to delivery were associated with a higher risk of IUGR ( P = 0.006, 14 trials) and lower mean birthweight ( P = 0.049, 27 trials). [39] This suggests that fetal growth benefits from maternal hypertension. In a GWAS on preeclampsia, genetic variants in the fetal genome near the FLT1 gene were significantly associated with the syndrome in 4380 cases and 310,238 controls. Interestingly, the association was strongest in offspring of LOPE patients without IUGR. FLT1 encodes antiangiogenic sVEGFR-1 in trophoblasts. The risk C allele of the lead SNP rs4769613 ( P = 5.4 × 10 −11 ) was associated with high concentrations of sVEGFR-1 in maternal blood in control pregnancies ( P = 0.04). [40] Maternal plasma levels of sVEGFR-1 are higher in cases of severe preeclampsia compared with cases without severe features, and are also higher in cases of early-onset preeclampsia compared with cases of LOPE. [41] There are several possible explanations for the stronger genetic association in cases of LOPE without IUGR. First, while placental sVEGFR-1 is shed in normal pregnancy, levels are significantly increased in cases of preeclampsia. Thus, sVEGFR-1 may be a physiological regulator of maternal blood pressure that is released by the fetus (placenta) during normal pregnancy. In cases of partially defective deep placentation, placental ischemia tends to be mild. Fetuses that carry preeclampsia-risk alleles at the FLT locus tend to secrete more sVEGFR-1 to elevate maternal blood pressure, which leads to increased placental perfusion and fetal growth. Therefore, these alleles may simultaneously increase the risk of preeclampsia and decrease the risk of IUGR.

Although maternal hypertension may benefit fetal growth, it is likely to be detrimental to the mother. In severe cases, hypertensive crisis could lead to cerebrovascular accident and maternal death. Thus, there might be a maternal response to fetal adaption to placental ischemia. It has been suggested that a maternal inflammatory response may counteract the fetus. A recent study using transcriptome profiling of unsupervised cluster placentas identified 3 clinically probable etiologies of preeclampsia. A subgroup of preeclampsia patients showed severe fetal growth restriction and evidence of maternal antifetal rejection, while the maternal parameters of disease severity, such as blood pressure and proteinuria levels, were less severe in these cases compared with canonical patients. [42] One possible explanation is that the maternal condition is relieved by restricting fetus growth. This view is supported by the observation that resolution of maternal hypertension follows fetal death in some patients with preeclampsia. [43] Our recent study identified a number of consistently hypomethylated probes that were associated with early-onset preeclampsia in different populations. The methylation levels of the validated probes were associated with clinical severity, and the samples with intermediate changes in methylation showed antagonistic fetal/maternal outcomes. [44]

Successful reproduction is the common interest of the mother and fetus. However, conflict between the mother and her fetus takes place when their interests diverge, resulting in antagonistic responses. Variations in these adaptive responses impact pregnancy outcomes. Meanwhile, common phenotypes of pregnancy outcome may represent the manifestation of different adaptive responses. For example, IUGR may be caused by severely defective deep placentation, the insensitivity of the fetus to ischemia, or the tolerance of the mother to placental releasing factors. Thus, individuals born with IUGR may have different genotypes that influence fetal growth and future predisposition to NCDs. This complexity represents a major challenge in identifying the genetic correlation between early development and NCD risk.

Epigenetic modifications link both genetic and environmental factors to long-term health

Epigenetics refers to “the study of molecules and mechanisms that can perpetuate alternative gene activity states in the context of the same DNA sequence.” [45] Epigenetic modifications, including DNA methylation, histone modifications, and noncoding RNAs, modify DNA bases and chromatin. This enables the establishment and maintenance of chromatin states that regulate gene expression transmitted across cell divisions.

For most differentiated somatic cells, epigenetic modifications buffer environmental variations and act as barriers to prevent changes in gene expression and cell identity. However, adaption responses to extreme environmental conditions during specific sensitive periods in early development can induce epigenetic programming, which can lead to long-lasting changes in the epigenome and predispose an organism to disease in adult life. [46]

Epigenetic modifications are thought to be reversible and are governed by a series of writers (that deposit them), readers (that interpret them), and erasers (that remove them). Both genetic and environmental factors are involved in epigenetic variations. Variations in the DNA sequence can influence epigenetic modifications in two ways: 1) changing the target sequences of modifications or 2) altering the genes encoding the epigenetic writers, readers, or erasers. Rare genetic mutations of implicated regions can also cause epigenetic disorders. For example, DNA methylation is one of the best-characterized epigenetic modifications. DNA methylation in the human genome predominantly occurs at the C5 position of cytosine in CpG dinucleotides. [47] Fragile X syndrome is a mental condition caused by the excessive expansion of a CGG repeat in the 5’ untranslated region of the FMR1 gene. [48] More than 200 repeats of the trinucleotide induce mRNA-mediated DNA methylation in the CGG repeat, resulting in gene silencing. [49] DNA methylation is catalyzed by the DNA methyltransferase family, which includes DNMT1, DNMT3A, and DNMT3B (the writers). Rare de novo heterozygous mutations in the DNMT3A gene cause Tatton-Brown-Rahman syndrome, a overgrowth disorder characterized by a distinctive facial phenotype and intellectual disability. [50] Further, somatic mutations of the same gene are frequent in cases of acute myeloid leukemia. [51] Interestingly, two other genes that encode epigenetic writers, EZH2 and NSD1 , are both associated with developmental growth disorders and hematological malignancies. [52] MECP2, which binds methylated CpGs, is a reader of DNA methylation that can both activate and repress transcription. [53] Mutations in the MECP2 gene are the main genetic causes of Rett syndrome, a progressive neurologic developmental disorder with X-linked dominant inheritance. [54] The ten-eleven translocation (TET) enzymes, which are encoded by TET1 , TET2, and TET3 , oxidize the C5 position of cytosines and are important erasers of DNA methylation. Somatic mutations in TET genes are frequent in several kinds of hematological cancer. [55] In contrast, transposable elements are frequent targets of epigenetic silencing. Abnormal epigenetic modifications may activate transposable elements, and therefore influence genome integrity and induce de novo mutations. For instance, human neuronal progenitor cells carrying MeCP2 mutations have been found to have heightened susceptibility to LINE-1 retrotransposition. [56]

Environmental factors can have direct influences on the cellular epigenome. Most epigenetic writers and erasers are enzymes for which activity is mediated by the availability of substrates, cofactors, and allosteric regulators. A number of metabolites derived from diverse metabolic pathways, including the one-carbon metabolism, the tricarboxylic acid cycle, β-oxidation, glycolysis, and hexosamine biosynthesis, are used as substrates and cofactors in epigenetic modifications. [57] Therefore, environmental factors, such as diet, microbiome, temperature, malnutrition, and chemical exposure can affect cellular metabolism and change the activity of chromatin-modifying enzymes, leading to changes in the epigenome. For example, epigenetic changes have been found to persist for periods longer than 60 years in individuals prenatally exposed to the Dutch Hunger Winter. [58]

Among epigenetic modifications, DNA methylation is more stable and more suitable for high-resolution assay platforms than histone modifications or non-coding RNA expression. High throughput platforms based on bisulfite conversion are highly quantitative and reproducible, offering high sensitivity to detect small changes from limited amounts of DNA. [59] Epigenome-wide association studies have found many loci with small (<10%) changes in intermediate methylation levels that are associated with complex phenotypes of NCDs. [60] This paradigm is in stark contrast to the observation of imprinted genes or malignant cells that have large differences in methylation level in genomic regulatory regions and clear gene expression changes. Although some changes in DNA methylation may reflect fetal genetic predisposition to disease, [61] others have been found to be reproducibly associated with specific environmental factors. [62] The presence of differential methylated cytosines in NCDs reflects the comprehensive effect of genetic and environmental factors. Therefore, the DNA methylome in peripheral, easy-to-access tissues in early stages of life, such as the placenta, umbilical cords, and fetal membranes, may be ideal for identifying the biomarkers for both genetic risk and early developmental stress associated with NCDs.

Genetic studies of children born after assisted reproduction

The use of assisted reproductive technologies (ART) has grown dramatically, contributing to millions of successful birth worldwide and accounting for more than 4% of all newborns in some European countries. [63] Assisted reproduction is redefining human society and biology, as many infertile couples may transmit their genes to subsequent generations. The long-term health of children born via ART is still unclear because they are too young to evaluate their incidence of age-related NCDs. However, ART children have a specific genetic background, and they tend to be exposed to some environmental stressors. ART children may be a promising cohort for studying the genetic basis of DOHaD theory.

ART procedures are generally used by couples who are infertile, which is defined as “failure to achieve clinical pregnancy after 12 months or more of regular unprotected sexual intercourse”’. [64] The infertile population is known to have an increased prevalence of NCDs. For example, polycystic ovary syndrome (PCOS), which affects 5% to 20% of women of reproductive age worldwide, is the most common cause of anovulatory infertility. [65] Patients with PCOS are at risk of many other NCDs such as coronary heart disease, stroke, and obesity. [66] Genetic studies have indicated causal roles in PCOS etiology for elevations in body mass index and insulin resistance. However, PCOS susceptibility is associated with alleles that raise the menopausal age and genes involved in DNA repair, suggesting a mechanism resulting in the retardation of ovarian ageing. [67] ART children are likely to inherit genes associated with susceptibility to infertility and other NCDs, or quantitative traits associated with infertility. Meanwhile, the population of parents using ART tends to be older, which is associated with an increased number of de novo mutations in offspring. [68] Moreover, social-economical factors affect the accessibility of ART treatments. ART clinic remains absent, inaccessible or unaffordable for many infertile couples in the world. [69] Those healthy subfertile couples with higher socioeconomic status have more opportunities to transmit their genes. Although the genetic background of ART children is a confounding factor in many epidemiological studies, but it can be overcomed in genetic studies using family-based genetic data. For example, live birth is a key phenotype for ART children. The classic transmission/disequilibrium test can be used to identify the genetic loci associated with live birth in nuclear families and investigate changes of gene pool between parents and offspring.

Compared with naturally-conceived children, ART children are exposed to many environmental stressors associated with the assisted reproductive procedure. For example, a pivotal step in most in vitro fertilization protocols is controlled ovarian stimulation (COS), in which exogenous gonadotrophins are used to retrieve multiple oocytes. COS may be implicated in adverse perinatal outcomes because it involves altering the embryonic genome and epigenome. [70] The oocyte yield after COS is highly variable, and in some cases, more than twenty mature oocytes are acquired in one cycle. However, in a natural menstrual cycle, only one or two oocytes from dominant follicles would undergo ovulation simultaneously. The number of oocytes retrieved after COS, which is influenced by genetic factors, [71] is positively associated with the live birth rate up to 20 oocytes. [72] However, the incidence of severe ovarian hyperstimulation syndrome, which is associated with adverse developmental outcomes in offspring, increases significantly with the number of oocytes, particularly if more than 18 oocytes are retrieved. [72] Children born to ovarian-hyperstimulated women display cardiovascular dysfunctions and reduced intellectual ability. [73,74] Therefore, the genetic factors associated with oocyte number in COS have pleiotropic effects: although women who carry the genes associated with a higher number of oocytes retrieved have a greater chance of giving birth to a child after assisted reproduction, their children may have a greater risk of NCDs later in life. Besides COS, other steps in ART, including in vitro maturation of oocytes, intracytoplasmic sperm injection, in vitro culture of the embryo, cryopreservation and thawing of the gamete and embryo, and preimplantation genetic testing, may also negatively impact the early development of ART children. [75] Population-level changes in the genetic responses to these environmental factors would be very informative with respect to the mechanisms of development.

Although it is quite difficult to conduct detailed investigations regarding implantation failure events before initiation of pregnancy in naturally-conceiving women, such medical records often exist for individuals in the ART cohort. Thus, it is possible to investigate the genetic factors influencing success of embryo implantation leading to pregnancy in ART-treated women. A genetic association study found that a common functional p53 Pro allele was associated with increased rates of blastocyst implantation failure in in vitro fertilization patients. Selected alleles in SNPs in the LIF , Mdm2 , Mdm4 , and Hausp genes, each of which regulates p53 levels in cells, were also enriched in in vitro fertilization patients. [76] Despite these costs, the p53 Pro allele is associated with an increased lifespan, and previous positive selection for alleles in the p53 pathway has been identified in contemporary white and Asian populations. ART itself may also influence human evolution, as has been previously discussed. [77] There are several steps of natural and artificial selection during ART treatment and favored traits may differ between natural reproduction and ART. As a result, only approximately 5% of fresh oocytes produce a baby in ART cycles. [78] Identifying the genetic factors that confer benefits to reproductive success during ART and their potential pleiotropic effects on NCDs will be helpful in predicting the long-term health of ART children. Additionally, such information may also provide insight regarding the genetic mechanisms of DOHaD theory.

The DOHaD theory was formulated based on the well-established association between adverse early environmental events and the increased risk of adult NCDs. In this article, I have reviewed the genetic hypothesis of the DOHaD theory, namely, that genetic variants associated with early development have pleiotropic effects that contribute to the risk of NCDs. This hypothesis is not incompatible with the emphasis on environmental factors in the DOHaD theory, as evidence suggests that the environment of early human development is shaped by crosstalk between the fetal and the maternal genome. Moreover, the interplay between DNA sequence variations and environmental stresses programs the epigenome, resulting in long-term effects on phenotypes. Interestingly, some risk alleles of NCDs are under positive selection, suggesting that they play beneficial roles in reproduction and early development.

Until now, few genetic loci linking early development and adult NCDs had been identified. Both kinds of phenotypes are highly polygenic and any associated genetic loci have very small effect sizes. Importantly, the genetic correlation between early development and adult NCDs will be caused directly by the genome of the child, or indirectly by the genomes of the parents. New methods are needed to improve the power of screening for genetic correlations between pleiotropic effects. Meanwhile, certain intermediate phenotypes during reproduction may help to identify subclasses of cohorts.

Acknowledgments

Author contributions.

XZ drafted and revised this manuscript and approved the final submission.

Financial support

This work was supported by the National Key Research and Development Program of China (No. 2018YFC1005001), the National Natural Science Foundation of China (No. 81871180) and the Innovative Research Team of High-Level Local Universities in Shanghai, China; all to XZ.

Conflicts of interest

The authors declare that they have no conflicts of interest.

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assisted reproduction; DOHaD; genetic pleiotropy; non-communicable diseases; positive selection

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What Is Developmental Psychology?

Conditions treated, training and certifications.

Developmental psychology is the study of how humans grow, change, and adapt across the course of their lives. Developmental psychologists research the stages of physical, emotional, social, and intellectual development from the prenatal stage through infancy, childhood, adolescence, and adulthood.

This article covers developmental psychology, including the definition, types, life stages, and how to seek treatment when necessary.

seksan Mongkhonkhamsao / Getty Images

Defining Developmental Psychology

According to the American Psychological Association (APA), developmental psychology is a branch of psychology that focuses on how human beings grow, change, adapt, and mature across various life stages. Developmental psychology is also known as human development or lifespan psychology.

In each of the life stages of developmental psychology, people generally meet certain physical, emotional, and social milestones. These are the major life stages, according to developmental psychologists:

• Prenatal development: Developmental psychologists are interested in diagnoses, such as Down syndrome, that might be noticed during the prenatal (before birth) stage. They also investigate how maternal behaviors (behaviors of the pregnant parent), such as nutrition and drug use, could affect the developing fetus.
• Early childhood: Developmental psychologists are interested in whether young children are meeting key milestones, such as walking, talking, and developing fine motor skills (coordination in the hands, fingers, and wrists). They might also be interested in a child’s attachment to their parents and other caregivers.
• Middle childhood: In this stage, children learn about the world and acquire knowledge through experimentation, questioning, and observation. They begin to develop logical and moral reasoning skills.
• Adolescence: Adolescence is a time of major strides in terms of personal development and identity formation. Teens and young adults might experiment with various identities, career choices, or areas of interest.
• Early adulthood: During early adulthood, most people are focused on preparing for the rest of their lives through a focus on education, career, and financial independence. Romantic relationships, marriage, family-building, setting down “roots,” and child-rearing are often a focus of this life stage.
• Middle adulthood: Middle-aged adults are often focused on helping the next generation, whether in their own family or their community. They are also often interested in the legacy they’ll leave behind.
• Older adulthood: In addition to physical health challenges, older people might face issues like dementia or cognitive decline (decline in thinking, remembering, and reasoning). Older adults also often need to reflect on their lives, tell their stories, and find meaning and peace within the aging process.

The Origins of Developmental Psychology

During its early development as a branch of psychology in the late 19th and early 20th centuries, developmental psychology focused on infant and child development. As the field grew, so did its focus. Today, developmental psychologists focus on all stages of the human lifespan.  

Theories of Developmental Psychology

As developmental psychology grew over time, various researchers proposed theories about how to understand the process of human development. Depending on their training, a developmental psychologist might focus on a specific theory or approach within the field. 

These are a few of the major branches of developmental psychology.

Psychosocial Developmental Theory

Building on Austrian neurologist and the founder of psychoanalysis Sigmund Freud’s theory of psychosexual development , psychologist Erik Erikson proposed a lifespan theory that included eight stages of psychosocial development .

Each of the stages corresponds to both an age range and a core “crisis” (such as trust vs. mistrust in infancy) that must be resolved before someone can move on to the next.

Cognitive Developmental Theory

Swiss psychologist Jean Piaget’s theory of cognitive development focuses on how children and youth gradually become able to think logically and scientifically. Piaget proposed that cognition develops through four distinct stages of intellectual development, beginning at birth and ending at age 12.

Attachment Theory

Attachment theory , originally developed by psychoanalyst John Bowlby, establishes the importance of a supportive, steady, and loving caregiver in infant and child development. If a child doesn’t establish such a connection, or if they experience parental separation or loss, they might continue to struggle with healthy attachments as they get older.

Sociocultural Developmental Theory

While Bowlby considered the importance of the immediate family in child development, psychologist Lev Vygotsky’s sociocultural developmental theory looks at the role of society. Cultural influences and beliefs can have a profound impact on how a person views their own identity and relates to others.

Developmental psychologists can help people address developmental issues in order to reach their full potential. 

Some of the conditions a developmental psychologist might treat include:

• Learning disabilities
• Intellectual disabilities
• Developmental delays
• Motor skill delays
• Issues with social and emotional development
• Auditory processing (hearing) disorder
• Autism spectrum disorder (ASD)
• Speech and language delays
• Mental health conditions like anxiety and depression, especially related to life stages

The training required to become a developmental psychologist is similar to that in other subfields of psychology. Most developmental psychologists start with an undergraduate degree in psychology or a related field, followed by a master’s degree and a doctoral degree (PhD). 

There are many master’s, graduate certificate, and PhD programs in developmental psychology in the United States. Some focus on a certain part of a person's lifespan, such as child and adolescent development. In addition to research and teaching, graduates may participate in a practicum or internship to pursue licensing as a therapist. 

When to Seek Treatment

If you're concerned that your child is facing a developmental delay, a developmental psychologist can assess them to ensure that they are meeting their milestones. It's best to seek an assessment, diagnosis, and treatment early, so intervention can begin as soon as possible.

Examples of when to see a developmental psychologist may include:

• An infant is struggling to bond with their parents.
• A toddler is missing milestones, such as walking or developing speech.
• A school-aged child is not progressing appropriately in reading or writing.
• An adolescent is facing challenges related to social and/or emotional development.

A developmental psychologist might perform physical and/or cognitive testing to diagnose your child or refer them to another specialist, including the following:

• Physical therapist (helps people improve movement and manage pain)
• Occupational therapist (helps people adjust to everyday activities after injury, illness, or disability)
• Speech-language pathologist (treats speech, language, and social and cognitive communication)
• Psychotherapist (uses talk therapy to treat mental health conditions)
• Neurologist (medical doctor who treats disorders of the brain, spinal cord, and nerves)
• Psychiatrist (medical doctor specializing in mental health conditions)

A developmental psychologist will also likely ask you and your child questions about issues in areas of their life such as friends, behavior, or school performance.

In addition to working with infants and children, developmental psychologists can also help people at any stage of life. In particular, many older adults benefit from working with a developmental psychologist if they're experiencing symptoms of dementia, ill health, or cognitive decline.

Developmental psychology is the study of how human beings grow and change throughout their lives. Many developmental psychologists focus on the intellectual, social, emotional, and physical development of infants, children, and adolescents. Others treat and assess people of all ages. 

Developmental psychologists can treat issues such as developmental delays, intellectual disabilities, learning disabilities, speech and language delays, motor skill delays, dementia, anxiety, depression, auditory processing disorder, autism spectrum disorder, and more. They also make referrals to other specialists, such as physical therapists, psychiatrists, and speech-language pathologists. 

American Psychological Association. Developmental psychology .

Maryville University. What is human development and why is it important ?

American Psychological Association. Developmental psychology studies human development across the lifespan .

Liberty University. Theories of psychosocial development .

Oklahoma State University Library. Cognitive development: the theory of Jean Piaget .

University of Illinois Psychology Department Labs. Adult attachment theory and research .

Massey University. Vygotsky .

Centers for Disease Control and Prevention.  Child development - developmental monitoring and screening .

Centers for Disease Control and Prevention. CDC's developmental milestones .

By Laura Dorwart Dr. Dorwart has a Ph.D. from UC San Diego and is a health journalist interested in mental health, pregnancy, and disability rights.

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• Product Management

MoSCoW Method: How to Make the Best of Prioritization

Prioritization played a significant role in the success of most feature-rich apps, such as Slack and GitLab . Initially, they offered a limited set of functionalities that were essential for their users. With time, this set was supplemented with other features. Railsware is going to share its own style of prioritizing and show you how we use the MoSCoW method to get long lists of tasks done.

Why do you need prioritization?

As a rule, the daily routine includes a bunch of tasks. Ideally, you’ll have enough time and energy to cover all of them – but it just might happen that the number of tasks is immense and the resources available are not in abundance. That’s where prioritization comes in.

This term denotes a process to filter what you have to do in order of importance or relevance. For example, if you’re building a house, you are not likely to begin with the roof or walls until your foundation is done. Of course, things are much more complicated in the web development industry, and this example cannot reveal the full-scope value of setting priorities.

Complex projects and numerous startups make use of advanced prioritization techniques. These usually consist of frameworks known for specific requirements or rules that improve decision-making. Success in prioritization often determines the success of the company itself. Getting caught up in pending and undone tasks is a straight road to failure. That’s why businesses pay particular attention to which prioritization methods to use. There are quite a few of them, but they all have some common characteristics, such as orientation towards input (internal or external) and quantitative or qualitative tools.

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External orientation means that you need to involve stakeholders outside the development team to set priorities, while the internally-oriented methods can be executed purely in-house. Quantitative methods entail a deeper focus on numeric metrics in prioritization, and the qualitative one rests on expert opinions, votings, classifications to a greater extent. In view of this, they are traditionally divided into the following categories:

You can read about different Agile prioritization techniques in detail here . If you need, we’ve also gone more in depth on what Agile product development is in a separate article.

Railsware prefers a technique developed by Dai Clegg way back in 1994. Initially, it was named MSCW, but two o’s were added to improve pronounceability. This also made it sound like the capital city of Russia. Let’s see how it works.

What is MoSCoW?

To understand the gist of the MoSCoW method, we need to look at its origin – the dynamic systems development method (DSDM). It is a framework for Agile project management tailored by practitioners with the aim of improving quality in rapid app development (RAD) processes. A hallmark of DSDM projects is strictly determined quality, costs, and time at an early stage. In view of this, all the project tasks have to be allocated by importance. The need for managing priorities triggered the invention of a specialized prioritization mechanism.

This mechanism was implemented via MoSCoW – a simple yet powerful solution to set priorities both with and without timeboxes. However, it shows better efficiency if you have a certain deadline for a task, feature, subfeature, functionality, etc. The framework is applicable to all levels of project prioritization from top to bottom, as well as to all functions and focus areas.

The MoSCoW abbreviation (except for the o’s) is carved with first letters of the priority categories it works with. These are Must-haves, Should-haves, Could-haves and Won’t-haves. And that’s how you can define which task falls into which category.

Prioritization rules

These rules or requirements estimate the importance of any task/process/feature/etc. Each company or work team uses its own approach to setting requirements, but, in general, they do not differentiate much and look as follows.

These are top-priority requirements, which shape the foundation of the major pipeline. Avoiding them means blocking the entire project or further activities. As a rule, product ideation depends entirely on defining must-haves using such pointers as ‘required for launch’, ‘required for safety’, ‘required for validation’, ‘required to deliver a viable solution’, etc.

• Can we move forward with the project if this task is undone? – if NO , it’s MUST .

Should-haves

This type of requirement is of secondary priority. Should-haves do not affect the launch and, traditionally, are considered important but not crucial. They differ from must-haves by the availability of a workaround. Therefore, the failure of a should-have task is unlikely to cause the failure of the entire project. If you’re building a product, it will still be usable even if these requirements aren’t met.

• Will we move forward with the project if this task is done a bit later? – if YES , it SHOULD .

Could-haves

The next requirement is less important than the two previous ones but still wanted. If we compare could-haves with should-haves, the former is defined by a lower degree of adverse effect if omitted. Traditionally, the third-level priority requirements in the Agile framework MoSCoW are realized if a project is not highly constrained in time. Within the product development, we can call them low-cost tweaks.

• Can we sacrifice this task till the deadline? – if YES , it’s COULD .

Won’t-haves

You can also encounter this type of requirement under the name of would-have or wish-to-have, but these variants are not recognized by the Wiki . However, regardless of the chosen name, these requirements define the lowest priority for tasks that are unviable to implement with a particular budget and deadline. Won’t-have does not mean a complete rejection of something. It envisions reintroduction under favorable conditions in the future.

• Can we get back to it when things are going better? – if YES , it’s WON’T .

In search of the perfect tools and techniques, our team often modifies some well-known approaches and tailors them to our needs. This constant search and improvement led us to brand new product ideation and decision-making framework: BRIDGeS . BRIDGeS is a flexible approach for multi-context analysis suitable for building effective product strategies, solving operational and strategic problems, making day-to-day decisions , and more. Find out how to use BRIDGeS and what advantages BRIDGeS can bring to your team .  

MoSCoW is another tool that we modified to make it even more flexible and versatile. Below, we share our findings to help your team nail prioritization in a more efficient way.

How the Railsware team modified MoSCoW

The main difference between the classical MoSCoW and our version of this technique is that we added another level of prioritization within such groups as Must, Should, and Could. Each of these groups of requirements got another 4 complexity categories :

• 3 – most heavy and unclear requirements
• 2 – heavy complexity
• 1 – normal complexity
• 0 – easiest and the most urgent tasks within the group

This way, when a requirement gets, let’s say, the priority Must, we can also add a numeric matter to the letter M. For instance, our sprint can include several M2 tasks, one M1 task, and three S1 tasks.

When the task is marked with the priority “3” (M3/S3/C3), it most likely means that its scope is too large and complex to be fulfilled fast. You need to decompose it into smaller, manageable chunks and prioritize them as well. This way, from one M3 requirement, you can get a bunch of M2, S1, and C1 tasks, for example.

Sometimes, M, S, C, and W letters are not enough and we may also need an Urgent Must (UM) mark. UMs are the most critical things, such as hotfixes, bug fixes, and patches, which block the work of the whole team. From our experience, we recommend you to fix these tasks ASAP, as they hinder the team’s productive work. So if you set any task as UM, you should ignore all other tasks until the UM task is fixed. In normal situations, your bug tracking system shouldn’t have UMs.

Why do Urgent Must tasks appear? Often, UMs are the Must-haves that your team ignored before the deployment phase or missed during the QA phase. Pay attention to these tricky cases, and try to solve them before they become an obstacle.

Advantages of the modified MoSCoW approach

When we got an additional level of priorities within the MoSCoW system, we felt the following improvements:

• No need to run several rounds of task prioritization . When you have six Must-have requirements, you can’t understand which of them are the most critical or complex and run another round of prioritization. Our approach allows us to set priorities and clearly understand the importance and complexity of each task from the first round.
• Saved time . The ability to set all priorities at once saves time for all the team members who take part in the prioritization process.
• More balanced sprints. A sprint that consists only of Must-have tasks has little chance of being fulfilled. Must-haves are usually more complex requirements that guarantee the viability of a product, meaning their implementation takes more time and concentration from a developer. To dilute high-importance work with some low-hanging tasks, you can add some S0, C0, or S1 tasks to the sprint so that users get a bit more full-featured functionality of the main Must-have flows.
• More pleasant products for end users . While M3 and M2 tasks are usually crucial things necessary for the product viability, Could- and Should-haves may represent more pleasant things (changing a theme, additional filters, notifications, etc.) 

How to use MoSCoW

Everything looks simple in theory, but is it in practice? Let’s check out how a traditional MoSCoW analysis of functionality prioritizing works through the example of a regular web application. As a sample, we’re going to use basic functions taken from one of the Railsware products .

List all tasks

Prioritize cards.

Based on particular requirements for budget and time, we can single out the most fundamental features to be implemented in the minimum viable product . After the priority analysis, we’ve got the following:

• A user MUST sign up.
• A user MUST log in.
• A user MUST reset password.
• A user MUST open a time-tracking page.

The top-priority tasks are followed by important, though not vital,functionalities for the app. These are:

• A user SHOULD choose the billing system.
• A user SHOULD delete an account.
• A user SHOULD choose time-tracking options.

The evolution of the app does foresee its availability on mobile devices. However, this task is only nice-to-have at this point.

• A user COULD install a mobile app version.

And now the least-priority feature. It aims at enhancing the user experience once the app is on track. Theme selectability is definitely not what we’re going to make now, so this feature is saved for later.

• A user WON’T choose the app’s visual theme THIS TIME.

Restructure cards according to their priority

This step allows you to see the quantitative ratio of high and low priority tasks.

The most difficult thing about prioritization is to be icily intelligent and focus on the essential tasks to be done. Otherwise, you can get into the EVERYTHING-IS-MUST trap , according to which any feature like the billing system option or mobile app availability turns into the must-have.

And that’s why the MoSCoW Agile method is cool. It allows you to define a basic feature set, which has top priority and emphasizes that you do not need to abandon anything. The healthy balance of must-haves + should-haves is 50% of the entire scope. All (or almost all) of the tasks will be implemented later but in the order of their importance to your goal. The goal of this example is to build an MVP , and the categorization above shows the expected progress of the app’s functionality.

How to use modified MoSCoW

We took the same example with all the tasks listed above to showcase how we apply our version of this prioritization technique.

Set priorities using the extended MoSCoW model

The main priority (Must, Should, Could, and Won’t) are still the same, however, we dived deeper to make a more precise priority estimation of each task. Here’s what we came up with:

• “A user can sign up” got an M2 mark. It is a complex task, but it’s not critically urgent.
• “A user can log in” got an M1 mark. The task is important but not that complex.
• “A user can reset password” got an M1 mark. 
• “A user can choose the billing system” got an S3 mark. It’s an important feature, but its scope is large and should be split.
• “A user can delete the account” got an S2 mark. 
• “A user can open a time-tracking page” got an M2 mark. 
• “A user can choose time-tracking options” got an S1 mark. This is a low-hanging feature that can be taken to a sprint to balance the workload.  
• “A user can install a mobile app version” got a C3 mark. This epic is too large to be implemented in one sprint. Its scope should be split into smaller tasks and prioritized as well.
• “A user can choose the app’s visual theme” got the same priority mark – Won’t, which we do not decompose.

Our modified approach provides a better understanding of the task’s priority and complexity and shows the parts that need to be reconsidered. This way, it’s easier to plan a balanced sprint, taking only tasks that can be implemented (all cards with the priority “3” should be split into smaller tasks) and some small tasks that allow your team to reduce the workload. 

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MoSCoW pros and cons

The framework is quite popular among Agile projects with fixed timeboxes since it allows for managing the requirements for a specific release of a product. This prioritization method has proved its efficiency and reliability within our company as well, and we do recommend it to our clients. However, it is not perfect of course, and an unbiased look can reveal some flaws associated with MoSCoW technique. Let’s take a look at its strengths and weaknesses.

MoSCoW prioritization at Railsware

Let’s take a look at how we set priorities within the company.

Product development: we rest upon a roadmap where the product features and the order of their implementation are specified. As a rule, we leverage MoSCoW to define which feature goes first, which comes second, and so on, taking into account their importance and the interdependence of features. Must-haves and Should-haves are meant for the product release. Could-haves and Won’t-haves are postponed for the future.

HR and recruitment: prioritization rests upon such requirements as the demand for particular expertise, budget availability, timebox (how urgently we need this expertise), and so on. We leverage the similar patterns of setting priorities in other focus areas including on-boarding, branding, marketing, etc.

The biggest challenge of the methodology is that all stakeholders must be familiar with enough context to estimate features correctly. Besides, stakeholders that represent different functions like sales, development, marketing have their own vision of setting priorities, which not always works towards correct prioritization. Investors usually treat all features as Must-haves from their broad-based perspective and need them done without any respect of their implementation order.

Railsware has a Holacratic organizational structure . We take advantage of collective leadership based on the RASCI model and make decisions on different things including prioritization through voting. Team members can choose from several options like really want, want and don’t want. Each option implies a particular point. The option with the biggest point total has the highest priority. For small contexts, a responsible role (team leader, project manager, etc.) can be in charge of setting priorities on his/her own.

MoSCoW alternatives you may find useful for your project

Railsware uses Agile framework MoSCoW heavily and is pleased with it. However, it does not mean that we are closed to other solutions. Besides, a good product manager must consider the key product metrics and build the prioritization according to them. So here are some other worthwhile techniques that you may benefit from.

With this framework, you can define how happy the users are with product features. The Kano Model rests on a questionnaire, which is used to learn users’ attitude to a particular feature (like, expect, dislike, neutral, etc.). Visually, the model can be expressed via a two-dimensional diagram where the vertical axis is responsible for the level of user satisfaction (from totally frustrated to incredibly happy) and the horizontal one shows either how much was invested in the feature (Investment), how well was it implemented (Implementation), or how much users benefit from it (Functionality).

Categorization of requirements includes four types that are prioritized in the following order: must-be, performance, attractive, and indifferent. Must-bes are some basic things that users generally expect. Performance (also known as One-Dimensional) requirements are the golden mean and allow you to increase the satisfaction level. Attractive requirements are those that improve user experience. These are nice-to-haves or could-haves according to MoSCoW. Indifferent ones are less prioritized and sometimes even entirely omitted.

Value vs. Complexity

This prioritization technique is one of the simplest. You can encounter it under the names of Value vs. Cost or Value vs. Effort as well. The method feels intuitive and is aimed at maximizing value delivery. Estimation of features’ importance rests upon how much effort is invested to implement them and how much value they will bring. Here is how it looks visually:

Wrapping up

The art of setting priorities shows the efficiency of your workflow. Railsware’s choice is the MoSCoW project management framework, which has made a good showing in versatile functionalities and products. However, it might be less useful for immense projects with multiple teams involved in the pipeline. We advise you to find an effective prioritization solution that fits your unique needs, and to always avoid getting caught up in countless pending tasks.

• Agile, DevOps and software development methodologies

MoSCoW method

What is the MoSCoW method?

The MoSCoW method is a four-step approach to prioritizing which project requirements provide the best return on investment (ROI). MoSCoW stands for must have, should have, could have and will not have -- the o's make the acronym more pronounceable.

A variety of business disciplines use the MoSCoW method. It enables everyone involved in a project to know what work to complete first and how that work helps increase revenue, decrease operational costs, improve productivity or boost customer satisfaction. On the business side, it can help stakeholders frame discussions about the importance of specific product features when choosing a software vendor. On the IT side, the MoSCoW method plays an important role in Agile project management by helping project teams prioritize story points.

Furthermore, prioritizing requirements enables project teams to understand the amount of effort and resources each project element requires. This knowledge improves the team's time management, makes the project more manageable, increases the likelihood of completion by deadline and optimizes ROI .

The MoSCoW method is also known as MoSCoW analysis , MoSCoW prioritization , MoSCoW technique and MoSCoW rules .

Prioritization of requirements

Before implementing the MoSCoW method, businesses must ensure the teams involved in the project and other stakeholders agree on the project objectives and the factors they use for prioritization. They should also establish plans for settling disagreements.

Next, teams should decide what percentage of resources they assign to each category. For example, they could allocate 20% of the resources to the could-have requirements, while giving 40% to must-haves and 30% to should-haves.

Once the teams and stakeholders gather requirements and reach agreements, then the teams can start assigning requirements to each of the following four categories.

1. M: Must have

This first category includes all the requirements that are necessary for the successful completion of the project. These are non-negotiable elements that provide the minimum usable subset of requirements.

Statements that are true for must-haves include the following:

• There is no point completing the project by its target deadline without this requirement.
• The final product or software would not be compliant or legal without this requirement.
• The final product or software would not be safe without this requirement.
• The final product or software does not deliver an effective solution without this requirement.

If there is any way to work around a particular requirement, teams should consider it a should-have or could-have element. Assigning requirements to the should-have and could-have categories does not mean the team won't deliver the element; it just reveals that it is not necessary for completion and, therefore, is not guaranteed.

2. S: Should have

This second category of requirements is one step below must have. It can prep requirements for future release without impacting the current project. Should-have elements are important to project completion, but they are not necessary. In other words, if the final product doesn't include should-have requirements, then the product still functions. However, if it does include should-have elements, they greatly increase the value of the product. Minor bug fixes, performance improvements and new functionality are all examples of requirements that could fall into this category.

Teams can distinguish a should-have element from a could-have element by assessing the amount of pain caused by leaving the requirement out. This is often measured in terms of the business value or the number of people affected by its absence.

3. C: Could have

This category includes requirements that have a much smaller impact when left out of the project. As a result, could-have requirements are often the first ones teams deprioritize -- must-have and should-have requirements always take precedence as they impact the product more. An example of a could-have is a desirable but unimportant element.

4. W: Will not have

This final category includes all the requirements the team recognizes as not a priority for the project's time frame. Assigning elements to the will-not-have category helps strengthen the focus on requirements in the other three categories, while also setting realistic expectations for what the final product does not include. Furthermore, this category is beneficial in preventing scope creep -- or the tendency for product or project requirements to increase during development beyond what the team anticipated.

The team can eventually reprioritize some requirements in the will-not-have group and work them into future projects; others are never used. To differentiate between these types of elements, teams can create subcategories within the will-not-have group to identify which requirements they should still implement and which they can ignore.

MoSCoW method for Agile

The Agile project management methodology breaks projects into small sections called iterations. Each iteration focuses on completing specific project elements in work sessions called sprints -- typically lasting two to four weeks. The MoSCoW method is frequently used within Agile project management to determine which elements -- including tasks, requirements, products and user stories -- the team should prioritize and which can be put on hold. These decisions make an Agile project schedule that enables teams to rapidly deploy solutions, more efficiently use resources, increase their flexibility and adaptability to changes, and more quickly detect issues.

Advantages of the MoSCoW method

The MoSCoW method is easy to use and understand. It can help individuals with prioritization, but it more greatly benefits project teams. Other advantages include the following:

• Resolves disputes and form agreements with stakeholders.
• Ensures a minimum viable product is produced.
• Sets priorities at different levels of the development pipeline.
• Enables categorizing requirements to rely on the expertise of the team.
• Can be used for both existing and new projects.

In addition, the MoSCoW method enables users to assign specific percentages of resources to each of the four categories. This action ensures resources are effectively managed ,and it optimizes productivity analysis.

Criticism of the MoSCoW method

However, there are some drawbacks with the MoSCow method, including the following:

• There is uncertainty surrounding will-not-have requirements and whether they are left out of the release or the entire project.
• There's no clear way to prioritize requirements within the same category.
• There is no reasoning for why one requirement is a must-have and the other is a should-have.
• If an organization's decision-making process excludes collective leadership, prioritization may become subjective and inefficient.

History of the MoSCoW method

The MoSCoW method has its roots in the dynamic systems development method -- an Agile project delivery framework that aimed to improve rapid application development processes.

Software development expert Dai Clegg created the MoSCoW method while working at Oracle , the multinational computer technology corporation. Clegg initially designed the prioritization technique for timeboxed projects and initiatives within releases.

Editor's note: This article was reformatted in 2023 to improve the reader experience.

Continue Reading About MoSCoW method

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MoSCoW Prioritization

What is moscow prioritization.

MoSCoW prioritization, also known as the MoSCoW method or MoSCoW analysis, is a popular prioritization technique for managing requirements. 

  The acronym MoSCoW represents four categories of initiatives: must-have, should-have, could-have, and won’t-have, or will not have right now. Some companies also use the “W” in MoSCoW to mean “wish.”

What is the History of the MoSCoW Method?

Software development expert Dai Clegg created the MoSCoW method while working at Oracle. He designed the framework to help his team prioritize tasks during development work on product releases.

You can find a detailed account of using MoSCoW prioritization in the Dynamic System Development Method (DSDM) handbook . But because MoSCoW can prioritize tasks within any time-boxed project, teams have adapted the method for a broad range of uses.

How Does MoSCoW Prioritization Work?

Before running a MoSCoW analysis, a few things need to happen. First, key stakeholders and the product team need to get aligned on objectives and prioritization factors. Then, all participants must agree on which initiatives to prioritize.

At this point, your team should also discuss how they will settle any disagreements in prioritization. If you can establish how to resolve disputes before they come up, you can help prevent those disagreements from holding up progress.

Finally, you’ll also want to reach a consensus on what percentage of resources you’d like to allocate to each category.

With the groundwork complete, you may begin determining which category is most appropriate for each initiative. But, first, let’s further break down each category in the MoSCoW method.

Start prioritizing your roadmap

Moscow prioritization categories.

1. Must-have initiatives

As the name suggests, this category consists of initiatives that are “musts” for your team. They represent non-negotiable needs for the project, product, or release in question. For example, if you’re releasing a healthcare application, a must-have initiative may be security functionalities that help maintain compliance.

The “must-have” category requires the team to complete a mandatory task. If you’re unsure about whether something belongs in this category, ask yourself the following.

If the product won’t work without an initiative, or the release becomes useless without it, the initiative is most likely a “must-have.”

2. Should-have initiatives

Should-have initiatives are just a step below must-haves. They are essential to the product, project, or release, but they are not vital. If left out, the product or project still functions. However, the initiatives may add significant value.

“Should-have” initiatives are different from “must-have” initiatives in that they can get scheduled for a future release without impacting the current one. For example, performance improvements, minor bug fixes, or new functionality may be “should-have” initiatives. Without them, the product still works.

3. Could-have initiatives

Another way of describing “could-have” initiatives is nice-to-haves. “Could-have” initiatives are not necessary to the core function of the product. However, compared with “should-have” initiatives, they have a much smaller impact on the outcome if left out.

So, initiatives placed in the “could-have” category are often the first to be deprioritized if a project in the “should-have” or “must-have” category ends up larger than expected.

4. Will not have (this time)

One benefit of the MoSCoW method is that it places several initiatives in the “will-not-have” category. The category can manage expectations about what the team will not include in a specific release (or another timeframe you’re prioritizing).

Placing initiatives in the “will-not-have” category is one way to help prevent scope creep . If initiatives are in this category, the team knows they are not a priority for this specific time frame. 

Some initiatives in the “will-not-have” group will be prioritized in the future, while others are not likely to happen. Some teams decide to differentiate between those by creating a subcategory within this group.

How Can Development Teams Use MoSCoW?

  Although Dai Clegg developed the approach to help prioritize tasks around his team’s limited time, the MoSCoW method also works when a development team faces limitations other than time. For example: 

Prioritize based on budgetary constraints.

What if a development team’s limiting factor is not a deadline but a tight budget imposed by the company? Working with the product managers, the team can use MoSCoW first to decide on the initiatives that represent must-haves and the should-haves. Then, using the development department’s budget as the guide, the team can figure out which items they can complete. 

Prioritize based on the team’s skillsets.

A cross-functional product team might also find itself constrained by the experience and expertise of its developers. If the product roadmap calls for functionality the team does not have the skills to build, this limiting factor will play into scoring those items in their MoSCoW analysis.

Prioritize based on competing needs at the company.

Cross-functional teams can also find themselves constrained by other company priorities. The team wants to make progress on a new product release, but the executive staff has created tight deadlines for further releases in the same timeframe. In this case, the team can use MoSCoW to determine which aspects of their desired release represent must-haves and temporarily backlog everything else.

What Are the Drawbacks of MoSCoW Prioritization?

  Although many product and development teams have prioritized MoSCoW, the approach has potential pitfalls. Here are a few examples.

1. An inconsistent scoring process can lead to tasks placed in the wrong categories.

  One common criticism against MoSCoW is that it does not include an objective methodology for ranking initiatives against each other. Your team will need to bring this methodology to your analysis. The MoSCoW approach works only to ensure that your team applies a consistent scoring system for all initiatives.

Pro tip: One proven method is weighted scoring, where your team measures each initiative on your backlog against a standard set of cost and benefit criteria. You can use the weighted scoring approach in ProductPlan’s roadmap app .

2. Not including all relevant stakeholders can lead to items placed in the wrong categories.

To know which of your team’s initiatives represent must-haves for your product and which are merely should-haves, you will need as much context as possible.

For example, you might need someone from your sales team to let you know how important (or unimportant) prospective buyers view a proposed new feature.

One pitfall of the MoSCoW method is that you could make poor decisions about where to slot each initiative unless your team receives input from all relevant stakeholders. 

3. Team bias for (or against) initiatives can undermine MoSCoW’s effectiveness.

Because MoSCoW does not include an objective scoring method, your team members can fall victim to their own opinions about certain initiatives. 

One risk of using MoSCoW prioritization is that a team can mistakenly think MoSCoW itself represents an objective way of measuring the items on their list. They discuss an initiative, agree that it is a “should have,” and move on to the next.

But your team will also need an objective and consistent framework for ranking all initiatives. That is the only way to minimize your team’s biases in favor of items or against them.

When Do You Use the MoSCoW Method for Prioritization?

MoSCoW prioritization is effective for teams that want to include representatives from the whole organization in their process. You can capture a broader perspective by involving participants from various functional departments.

Another reason you may want to use MoSCoW prioritization is it allows your team to determine how much effort goes into each category. Therefore, you can ensure you’re delivering a good variety of initiatives in each release.

What Are Best Practices for Using MoSCoW Prioritization?

If you’re considering giving MoSCoW prioritization a try, here are a few steps to keep in mind. Incorporating these into your process will help your team gain more value from the MoSCoW method.

1. Choose an objective ranking or scoring system.

Remember, MoSCoW helps your team group items into the appropriate buckets—from must-have items down to your longer-term wish list. But MoSCoW itself doesn’t help you determine which item belongs in which category.

You will need a separate ranking methodology. You can choose from many, such as:

• Weighted scoring
• Value vs. complexity
• Buy-a-feature
• Opportunity scoring

For help finding the best scoring methodology for your team, check out ProductPlan’s article: 7 strategies to choose the best features for your product .

2. Seek input from all key stakeholders.

To make sure you’re placing each initiative into the right bucket—must-have, should-have, could-have, or won’t-have—your team needs context. 

At the beginning of your MoSCoW method, your team should consider which stakeholders can provide valuable context and insights. Sales? Customer success? The executive staff? Product managers in another area of your business? Include them in your initiative scoring process if you think they can help you see opportunities or threats your team might miss. 

3. Share your MoSCoW process across your organization.

MoSCoW gives your team a tangible way to show your organization prioritizing initiatives for your products or projects. 

The method can help you build company-wide consensus for your work, or at least help you show stakeholders why you made the decisions you did.

Communicating your team’s prioritization strategy also helps you set expectations across the business. When they see your methodology for choosing one initiative over another, stakeholders in other departments will understand that your team has thought through and weighed all decisions you’ve made. 

If any stakeholders have an issue with one of your decisions, they will understand that they can’t simply complain—they’ll need to present you with evidence to alter your course of action.  

Related Terms

2×2 prioritization matrix / Eisenhower matrix / DACI decision-making framework / ICE scoring model / RICE scoring model

Prioritizing your roadmap using our guide

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COLLEGE FOOTBALL 25 Rankings Week Showcase

Who are the best teams in ea sports™ college football 25.

Hey College Football Fans,

Welcome back to the Campus Huddle! This week, we have a special “living” edition of the Campus Huddle, centered around Rankings Week.

So what is Rankings Week? 

It’s a time to celebrate various EA SPORTS™ College Football 25 rankings, from the Toughest Places to Play, to the Top Offenses and Defenses, to our final Team Power Rankings before the worldwide launch on July 19. Plus, we’ll have our Sights and Sounds Deep Dive coming Wednesday, showcasing the incredible and unique presentation features coming to EA SPORTS™ College Football 25.

The full Rankings Week schedule can be seen here:

TOUGHEST PLACES TO PLAY

We laid out the significant impact that Homefield Advantage can have on the outcome of games in EA SPORTS™ College Football 25 during our Gameplay Deep Dive Campus Huddle . Audio and in-game modifiers such as blurred routes, incorrect play art, confidence and composure affects, and screen shaking are some of the immersive impacts away teams and players will be forced to contend with. 

But not all Homefield Advantages are created equal. The Development Team worked to compile a list of the Top 25 Toughest Places to Play, factoring in historical stats such as home winning %, home game attendance, active home winning streaks, team prestige, and more.

Rankings are subject to change in future updates.

• Kyle Field - Texas A&M
• Bryant-Denny Stadium - Alabama
• Tiger Stadium - LSU
• Ohio Stadium - Ohio State
• Sanford Stadium - Georgia
• Beaver Stadium - Penn State
• Camp Randall Stadium - Wisconsin
• Gaylord Family Oklahoma Memorial Stadium - Oklahoma
• Doak S. Campbell Stadium - Florida State
• Ben Hill Griffin Stadium - Florida
• Autzen Stadium - Oregon
• Memorial Stadium - Clemson
• Neyland Stadium - Tennessee
• Jordan-Hare Stadium - Auburn
• Williams-Brice Stadium - South Carolina
• Michigan Stadium - Michigan
• Lane Stadium - Virginia Tech
• Rice-Eccles Stadium - Utah
• Darrell K. Royal - Texas Memorial Stadium - Texas
• Kinnick Stadium - Iowa
• Notre Dame Stadium - Notre Dame
• Spartan Stadium - Michigan State
• Donald W. Reynolds Razorback Stadium - Arkansas
• Albertsons Stadium - Boise State
• Davis Wade Stadium - Mississippi State

SIGHTS AND SOUNDS DEEP DIVE

In case you missed it, Kirk Herbstreit is back with our next Deep Dive, taking a look at the sights and sounds featured in EA SPORTS™ College Football 25. The Development Team spent years capturing countless traditions, mascots, fight songs, and more to the game, ensuring all 134 schools and fan bases were represented with pride. These elements make College Football special and unique, bringing the unmatched feeling of game day to your fingertips.  

For even more on the presentation elements and how they come to life, check out the latest Campus Huddle hosted by Senior Game Designer Christian Brandt.

OFFENSIVE/DEFENSIVE POWER RANKINGS

The Development Team meticulously examined hundreds of thousands of data points to arrive at our team power rankings. With help from our friends at Pro Football Focus (PFF), the team analyzed all 134 rosters, thousands of players, years worth of game film, and mountains of stats, ultimately arriving at our Team Power Rankings.

Here are the Top 25 offenses in EA SPORTS™ College Football 25: 

• Georgia - 94 OVR
• Oregon - 94 OVR
• Alabama - 91 OVR
• Texas - 91 OVR
• Ohio State - 89 OVR
• LSU - 89 OVR
• Miami - 89 OVR
• Colorado - 89 OVR
• Missouri - 89 OVR
• Clemson - 87 OVR
• Utah - 87 OVR
• Penn State - 87 OVR
• Ole Miss - 87 OVR
• Kansas - 87 OVR
• Arizona - 87 OVR
• NC State - 87 OVR
• Notre Dame - 85 OVR
• Texas A&M - 85 OVR
• Memphis - 85 OVR
• SMU - 85 OVR
• UCF - 85 OVR
• Florida State - 83 OVR
• Oklahoma - 83 OVR
• Virginia Tech - 83 OVR
• USC - 83 OVR

As the old saying goes, “Defense wins championships.” Here are the Top 25 defenses in EA SPORTS™ College Football 25:

• Ohio State - 96 OVR
• Oregon - 90 OVR
• Alabama - 90 OVR
• Clemson - 90 OVR
• Notre Dame - 90 OVR
• Michigan - 90 OVR
• Texas - 88 OVR
• Penn State - 88 OVR
• Utah - 88 OVR
• Florida State - 88 OVR
• Oklahoma - 88 OVR
• Iowa - 88 OVR
• Virginia Tech - 86 OVR
• Wisconsin - 86 OVR
• USC - 86 OVR
• Auburn - 86 OVR
• LSU - 84 OVR
• Texas A&M - 84 OVR
• Colorado - 84 OVR
• Oklahoma State - 84 OVR
• Louisville - 84 OVR
• North Carolina - 84 OVR
• Kansas State - 84 OVR
• Florida - 84 OVR

TEAM POWER RANKINGS

And the moment you’ve all been waiting for! Here are the Top Teams in EA SPORTS™ College Football 25.

• Georgia - 95 OVR
• Ohio State - 93 OVR
• Oregon - 93 OVR
• Alabama - 92 OVR
• Texas - 92 OVR
• LSU - 90 OVR
• Michigan - 88 OVR
• Miami - 88 OVR
• Texas A&M - 88 OVR
• Ole Miss - 88 OVR
• Colorado - 87 OVR
• Oklahoma - 87 OVR
• Wisconsin - 87 OVR
• USC - 87 OVR
• Virginia Tech - 87 OVR
• Oklahoma State - 87 OVR
• Iowa - 87 OVR

Let us know what you think! Join the conversation today by following EA SPORTS™ College Football 25 on social media and rep your school. Next week, we’ll have even more information to share including our Dynasty Deep Dive where we explore the ins and outs of the mode, recruiting, and more! 

College Football 25 launches worldwide on July 19th, 2024. Pre-order the Deluxe Edition* or the EA SPORTS™ MVP Bundle** and play 3 days early. Conditions and restrictions apply. See disclaimers for details. Stay in the conversation by following us on Facebook , Twitter , Instagram , YouTube , and Answers HQ .

Pre-order the MVP Bundle*** to make game day every day, and get both Madden NFL 25 and College Football 25 with exclusive content.

FOLLOW US @EASPORTSCollege

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College football 25 sights and sounds deep dive, college football 25 gameplay deep dive, welcome to college football 25.

Press Release | With less than one fifth of targets on track, world is failing to deliver on promise of the Sustainable Development Goals, warns new UN report

Achieving the SDGs – the best pathway to tackle global challenges – remains elusive

New York, 28 June – With just six years remaining, current progress falls far short of what is required to meet the Sustainable Development Goals (SDGs). Without massive investment and scaled up action, the achievement of the SDGs — the blueprint for a more resilient and prosperous world and the roadmap out of current global crises — will remain elusive, warns The Sustainable Development Goals Report 2024 , launched today .

A world in great upheaval

  The report reveals that only 17 per cent of the SDG targets are currently on track, with nearly half showing minimal or moderate progress, and over one-third stalled or regressing. The lingering impacts of the COVID-19 pandemic, escalating conflicts, geopolitical tensions and growing climate chaos have severely hindered progress.

According to the report, an additional 23 million people were pushed into extreme poverty and over 100 million more were suffering from hunger in 2022 compared to 2019. The number of civilian deaths in armed conflict skyrocketed in 2023. That year was also the warmest on record, with global temperatures nearing the critical 1.5°C threshold.

A moment of choice and consequence

  “This report highlights the urgent need for stronger and more effective international cooperation to maximize progress starting now,” said UN Secretary-General António Guterres. “With more than six years left, we must not let up on our 2030 promise to end poverty, protect the planet and leave no one behind.”

Urgent priorities:

• Financing development : The SDG investment gap in developing countries now stands at $4 trillion per year. Developing countries require more financial resources and fiscal space. Reforming the global financial architecture is crucial to unlocking the volume of financing required to spur sustainable development.
• Peace and security : The number of forcibly displaced people has reached an unprecedented level, nearly 120 million by May 2024. Civilian casualties spiked by 72 per cent between 2022 and 2023 amid escalating violence, highlighting the urgent need for peace. Resolving ongoing conflicts through dialogue and diplomacy is essential.
• Implementation surge : Massive investment and effective partnerships are needed to drive critical transitions in food, energy, social protection, digital connectivity and more.

Success stories and opportunities for action

The report spotlights examples of success and resilience that can be built upon through decisive action.

The remarkable recent strides in deploying renewable energy, for example, highlight a clear pathway to a just energy transition. Girls in most regions have achieved parity and even pulled ahead of boys in completing schooling at all levels. Increasing internet access by about 70 per cent in just eight years also illustrates how rapid transformative change is possible. Similarly, decades of progress against HIV/AIDS provide a template for overcoming other pandemics through global solidarity and funding for scientific breakthroughs.

“Time and again, humanity has demonstrated that when we work together and apply our collective mind, we can forge solutions to seemingly intractable problems,” said Li Junhua, UN Under-Secretary-General for Economic and Social Affairs.

Key moments for the SDGs

  The Summit of the Future , taking place on 22 to 23 September at UN Headquarters in New York, will be pivotal to getting the world back on track to achieving the SDGs. Deliberations at the Summit will include addressing the debt crisis that is holding so many developing countries back and the urgent need for reform of the international financial architecture.

According to the report, both the Financing for Development Conference and the World Summit for Social Development in 2025 will be key moments to drive SDG momentum. But as Mr. Li stressed: “The time for words has passed – the political declarations must urgently translate into actions. We must act now, and act boldly.”

Key findings:

• For the first time this century, per-capita GDP growth in half of the world’s most vulnerable nations is slower than that of advanced economies.
• Nearly 60 per cent of countries faced moderately to abnormally high food prices in 2022.
• Based on data collected in 2022 in 120 countries, 55 per cent of the countries lacked non-discrimination laws that prohibit direct and indirect discrimination against women.
• Increased access to treatment has averted 20.8 million AIDS-related deaths in the past three decades.
• Progress on education remains of grave concern, with only 58 per cent of students worldwide achieving minimum proficiency in reading by the end of primary school.
• Global unemployment hit a historic low of 5 per cent in 2023, yet persistent roadblocks remain in achieving decent work.
• Global capacity to generate electricity from renewable energy has begun expanding at an unprecedented rate, growing at 8.1 per cent annually for the past five years.
• Mobile broadband (3G or higher) is accessible to 95 per cent of the world’s population, up from 78 per cent in 2015.
• Record high ocean temperatures have triggered a fourth global coral bleaching event.
• External debt stock levels have remained unprecedentedly high in developing countries. About 60 per cent of low-income countries are at high risk of debt distress or already experiencing it.

For more information, please visit: https://unstats.un.org/sdgs/report/2024/

Hashtags: #SDGreport #SDGs #GlobalGoals

Media contacts (interviews available upon request):

Sharon Birch, UN Department of Global Communications, [email protected]

Helen Rosengren, UN Department of Economic and Social Affairs, [email protected]

Beginning to enable a set of new features for Windows Insiders in the Dev Channel on Build 26120.961

• Amanda Langowski
• Brandon LeBlanc

UPDATE 6/30: We have temporarily paused the enablement of these features to investigate a few issues reported by Windows Insiders. We plan to begin the enablement again shortly.

Hello Windows Insiders, we are beginning to enable the following new features, changes and improvements, and fixes to the Dev Channel for Insiders on Build 26120.961 who have turned ON the toggle (shown in the image below) to get the latest updates as they are available via Settings > Windows Update. We’re starting the enablement of these at a small percentage at first so not all Insiders in the Dev Channel with this toggle turned on will see all these features right away. And some features may show up while others might not just yet. We hope to further expand the enablement of these new features, changes and improvements, and fixes with the next new Dev Channel build. Insiders will need to reboot to see if they have received the enablement of these features.

New features gradually being rolled out to the Dev Channel with toggle on*

Narrator users can now use voice access to dictate text hands-free.

Narrator users can start using  voice access in Windows 11  to dictate text with voice and hear what is dictated. In addition, you can also use voice access to give Narrator commands. For example, “Turn on Narrator,” “speak faster,” “read selection,” “read next line,” etc.

To know the entire list of Narrator commands supported with voice access, click help icon (?) on the voice access bar, select “View all commands” and choose “Narrator commands.”

What will work:

• Start and set up voice access which includes downloading a speech model.
• Read a list of voice access commands and Narrator commands from voice access help menu.
• Changing voice access microphone state.
• Dictating text with voice and hearing back what was dictated.
• If you don’t use headphones for listening to the screen reader, the audio output from the screen reader may get picked up by voice access microphone, leading to unwanted behavior.

FEEDBACK: Send us feedback in Feedback Hub (WIN + F) under Accessibility > Narrator.

Auto Restart for Voice Access & New Voice Access Command for Windows Search

We are introducing auto restart for  voice access in Windows 11 . This feature ensures that voice access will automatically restart if it encounters any issues so that individuals with limited mobility can get back to using voice access as quickly as possible. Customers will no longer need to rely on alternative assistive technologies or assistance from others to reactivate voice access. Should voice access automatically restart due to a crash, we are making it easier to report those crashes once voice access restarts so the team can investigate and work on fixes.

We are introducing a new command for searching directly with Windows search. Users can now say the command Search “Entity”; Search Windows for “Entity”; or Search for “Entity” to search for their desired application or file in Windows (“Entity” is replaced with whatever application or file you want to search.)

FEEDBACK: Send us feedback in Feedback Hub (WIN + F) under Accessibility > Voice access.

Changes and Improvements gradually being rolled out to the Dev Channel with toggle on*

[start menu].

• This update starts the roll out of the new account manager on Start menu. When you sign in with a Microsoft account, the new design gives you a quick glanceable view of your account benefits and makes it easy to manage account settings.

[Windows Share]

• We are beginning to roll out the ability to copy files from the Windows share window. Just click the new copy button.

• Users will be able to now generate QR codes for URLs and cloud file links through the Windows share window to seamlessly share webpages and files across their devices. To try this out in Microsoft Edge, just click the share button in the Edge toolbar and choose “Windows share options”.

• To prevent accidentally closing the Windows share window, clicking outside the Windows share window will no longer close it. To close the Windows share window, just press the close button at the top right corner.
• If your Microsoft account uses a Gmail address, you can now send email to yourself from Windows share window and receive it in your Gmail account.

• We’re adding support for  Emoji 15.1  which introduces a small number of brand-new emoji such as head shaking horizontally and vertically, phoenix, lime, brown mushroom and broken chain. Other changes for Emoji 15.1 include Unicode’s decision to revert family combinations to symbol-like shapes. Windows has chosen to stay with our existing style that uses people in family combinations. We are also supporting the new directionality updates for person/man/woman walking, kneeling, with cane, running, manual wheelchair and motorized wheelchair. You can now select right facing or the original left facing orientation for these emoji.

[Windows Backup]

• If you have both Personalization and Other Windows settings toggled on under  Settings > Accounts > Windows backup , many of your sound settings (including chosen sound scheme) will be backed up which can be restored via the Windows Backup app.
• To ensure you don’t lose access to your Microsoft account, we’re beginning to roll out a new banner with a “Add now” button under Settings > Account for adding a recovery email address if you haven’t added one for your Microsoft account yet. This will only show if you are signed in with a Microsoft account.
• We are beginning to roll out updated visuals for the “Rename your PC” and “Change date and time” dialogs to match the Windows 11 visuals.

Fixes gradually being rolled out to the Dev Channel with toggle on*

[task manager].

• Updated the units (from MHz to MT/s) for DDR speed.
• Fixed an issue where the Safely Remove Hardware option for ejecting USB devices wouldn’t work if Task Manager was open.
• Did some work to ensure Task Manager releases process handles quickly when terminating processes.
• Made some more improvements to help with Task Manager reliability.
• We have improved the performance when changing the sort order.
• Made multiple improvements to overall accessibility of Task Manager, including improving keyboard focus, tab navigation, text scaling, names of items read out by screen readers, and more.
• We made it a little easier to resize Task Manager when trying to resize by grabbing the top of the window.
• Fixed an issue where some monitors would get stuck at a 60Hz refresh rate and couldn’t be set higher even though the monitor supported it, because dynamic refresh rate was stuck.

[Multiple desktops]

• Fixed an issue where the option to set a different wallpaper on each desktop wasn’t working.
• Fixed an underlying issue which could lead to some apps not starting on startup even though they were enabled as startup apps in Setting.
• Fixed an underlying issue which could lead to the pop up asking for permission to use location not appearing, which could lead to app issues without location access.
• Fixed an issue causing some Insiders to see a bugcheck with error DRIVER_IRQL_NOT_LESS_OR_EQUAL in recent flights.

Reminders for Windows Insiders in the Dev Channel

• Updates released to the Dev Channel are based off Windows 11, version 24H2 .
• Features and experiences included in these builds may never get released as we try out different concepts and get feedback. Features may change over time, be removed, or replaced and never get released beyond Windows Insiders. Some of these features and experiences could show up in future Windows releases when they’re ready .
• Many features in the Dev Channel are rolled out using Control Feature Rollout technology , starting with a subset of Insiders and ramping up over time as we monitor feedback to see how they land before pushing them out to everyone in this channel.
• Some features in active development we preview with Windows Insiders may not be fully localized and localization will happen over time as features are finalized. As you see issues with localization in your language, please report those issues to us via Feedback Hub.
• Windows Insiders in the Dev Channel who want to be the first to get features gradually rolled out to you*, you can turn ON the toggle to get the latest updates as they are available via Settings > Windows Update. Over time, we will increase the rollouts of features to everyone with the toggle turned on. Should you keep this toggle off, new features will gradually be rolled out to your device over time once they are ready.
• Because the Dev and Beta Channels represent parallel development paths from our engineers, there may be cases where features and experiences show up in the Beta Channel first.
• Check out Flight Hub for a complete look at what build is in which Insider channel.
• Copilot in Windows** is being rolled out gradually to Windows Insiders across our global markets. Customers in the European Economic Area will be able to download the Copilot in Windows experience as an app from the Microsoft Store .

Thanks, Amanda & Brandon