Developmental psychology is the branch of psychology that studies physical, cognitive, and social change throughout the lifespan.

In developmental psychology, we see major issues that are continually debated:

• Nature vs. nurture: How does our genetic inheritance (our nature) interact with our experiences (our nurture) to influence our development?

• Continuity vs. stages: What parts of development are gradual and continuous, like riding an escalator? What parts change abruptly in separate stages, like climbing rungs on a ladder?

• Stability vs. change: Which of our traits persist through life? How do we change as we age?

Longitudinal Studies: research that follows and retests the same people over time

Cross-Sectional Studies: research that compares people of different ages at the same point in time

A growing human is fully dependent on the human it inhabits, and the life they lead and the choices they make can have a huge impact on the development of their baby. Teratogens are agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause potential harm:

• Illness → While you cannot always prevent yourself from getting sick, certain illnesses should be avoided at all costs while pregnant, as they can affect the development of a fetus (ex. Zika virus).

• Genetic Mutations ` → Any alteration to genetic sequencing during pregnancy can lead to birth defects, developmental delays, and even miscarriages.

• Hormones → The placenta acts as the primary source of hormones during pregnancy, producing necessary hormones to support fetal development and maintain pregnancy. Any dysregulation of these hormones can impact development, leading to complications for both the mother and fetus.

• Environment

  • Pollution

  • Climate

  • Political unrest

  • Stress → Stress hormones can cause early delivery.

• Diet → Pregnant people are encouraged to eat lots of fruits and vegetables, and discouraged from deli meats, soft cheeses, fish, raw meat/eggs, sugar, spicy food, and fast food.

• Medicine → Certain medicines interfere with proper fetal development.

• Drugs → Drugs and alcohol should be strictly avoided during pregnancy. Fetuses exposed to certain drugs may experience withdrawal after birth, as well as, serious health complications and physical abnormalities.

  • Fetal Alcohol Syndrome: physical and cognitive abnormalities in children caused by excessive drinking during pregnancy

Having survived prenatal hazards, we as newborns came equipped with automatic reflex responses ideally suited for our survival. We withdrew our limbs to escape pain. If a cloth over our face interfered with our breathing, we turned our head from side to side and swiped at it. New parents are often in awe of the coordinated sequence of reflexes by which their baby gets food. When something touches their cheek, babies turn toward that touch, open their mouth, and vigorously root for a nipple. Finding one, they automatically close on it and begin sucking. Other adaptive reflexes include the startle reflex (when arms and legs spring out, quickly followed by fist clenching and loud crying) and the surprisingly strong grasping reflex, both of which may have helped infants stay close to their caregivers.

• Habituation: decreasing responsiveness with repeated stimulation → similar to sensory adaptation

• Maturation is the biological growth processes that enable orderly changes in behavior, relatively uninfluenced by experience. In other words, regardless of environment, as long as a baby is alive, it will continue to grow and develop, though the extent of that development depends on exterior factors. 

• A critical period is a time during someone's development in which a particular skill or characteristic is believed to be most readily acquired, and if not acquired by a certain time, it may be impossible to learn.

In the womb, your developing brain formed nerve cells at the explosive rate of nearly one-quarter million per minute. From infancy on, brain and mind—neural hardware and cognitive software—develop together. On the day you were born, you had most of the brain cells you would ever have. However, your nervous system was immature: After birth, the brain’s branching neural networks that eventually enabled you to walk, talk, and remember had a wild growth spurt. This rapid development helps explain why infant brain size increases rapidly in the early days after birth. The brain’s association areas—those linked with thinking, memory, and language—were the last cortical areas to develop. As they did, your mental abilities surged. 

Developing neural connections prepare our brain for thought, language, and other later experiences. Mark Rosenzweig, David Krech, and their colleagues raised rats either alone in an environment without playthings, or with other rats in an environment enriched with playthings that changed daily. In 14 of 16 repetitions of this basic experiment, rats in the enriched environment developed significantly more cerebral cortex (relative to the rest of the brain’s tissue) than did those in the impoverished environment.

Studies suggest that we consciously recall little from before age 3. But as children mature, this infantile amnesia wanes, and they become increasingly capable of remembering experiences, even for a year or more. The brain areas underlying memory, such as the hippocampus and frontal lobes, continue to mature during and after adolescence.

The developing brain enables physical coordination. Skills emerge as infants exercise their maturing muscles and nervous system. With occasional exceptions, the motor development sequence is universal. Babies roll over before they sit unsupported, and they usually crawl before they walk. Most toddlers have learned to walk by the time they’re 15 months old.

From two-dimensional objects falling on our retinas, we somehow organize three-dimensional perceptions that allow us to estimate that object’s distance from us. This ability is known as depth perception. 

Depth perception was studied in a number of visual cliff experiments by Eleanor Gibson and Richard Walk. Infants were coaxed to cross what appeared to be drop, most of whom refused to do so, indicating that they understood depth.

Adolescence is the transition period from childhood to adulthood, extending from puberty to independence, while puberty is the period of sexual maturation during which a person becomes capable of reproducing.

A flood of hormones, primarily estrogen (main female sex hormone) & testosterone (main male sex hormone), triggers another period of dramatic physical change during adolescence, when boys and girls enter puberty. Girls’ slightly earlier entry into puberty can at first propel them to greater height than boys of the same age. But boys catch up when they begin puberty, and by age 14, they are usually taller than girls. 

For boys, puberty’s landmark is the first ejaculation, which often occurs first during sleep (as a “wet dream”). This event, called spermarche, usually happens by about age 14. In girls, the landmark is the first menstrual period, menarche, usually within a year of age 12½. Genes play a major role in predicting when girls experience menarche. But environment matters, too. Early menarche is more likely following stresses related to father absence, sexual abuse, insecure attachments, or a history of a mother’s smoking during pregnancy.

During these growth spurts, the primary sex characteristics—the reproductive organs and external genitalia—develop dramatically. So do the nonreproductive secondary sex characteristics. Girls develop breasts and larger hips. Boys’ facial hair begins growing and their voices deepen. Pubic and underarm hair emerges in both girls and boys.

• Primary sex characteristics include the body structures (ovaries, testes, etc.) that make reproduction possible.

• Secondary sex characteristics are the non-reproductive sexual traits → side effects of puberty (breast growth, widening of hips, deepening of voice, body hair, etc.)

For boys, early maturation has mixed effects. Boys who are stronger and more athletic during their early teen years tend to be more popular, self-assured, and independent, though also more at risk for alcohol use, delinquency, and premature sexual activity.

For girls, early maturation can be a challenge. If a young girl’s body and hormone-fed feelings are out of sync with her emotional maturity and her friends’ physical development and experiences, she may begin associating with older adolescents, suffer teasing or sexual harassment, and experience increased rumination with anxiety or depression.

Adulthood begins sometime after a person’s mid-twenties, however, defining adulthood into stages is more difficult than defining stages during childhood or adolescence. Muscular strength, reaction time, sensory abilities and cardiac output begin to decline after the mid-twenties. Around age 50, women go through menopause (the time of natural cessation of menstruation), and men experience decreased levels of hormones and fertility. With age, sexual activity lessens. Nevertheless, most men and women remain capable of satisfying sexual activity, and most express satisfaction with their sex life.

In late adulthood, the immune system weakens, increasing susceptibility to life-threatening illnesses. Chromosome tips (telomeres) wear down, reducing the chances of normal genetic replication. But for some, longevity-supporting genes, low stress, and good health habits enable better health in later life.

Although physical decline begins in early adulthood, we are not usually acutely aware of it until later in life, when the stairs get steeper, the print gets smaller, and other people seem to mumble more. Visual sharpness diminishes, as does distance perception and adaptation to light-level changes. Muscle strength, reaction time, and stamina also diminish, as do smell, hearing, and touch. 

• Life expectancy keeps increasing (now about 79). Women outlive men by about 4 years and outnumber them at most ages.

• The body’s disease-fighting immune system weakens, making older adults more susceptible to life-threatening ailments such as cancer and pneumonia.

• Older people take a bit more time to react, to solve perceptual puzzles, and to remember names. Brain regions important to memory begin to atrophy during aging. 

• Exercise slows aging. Active older adults tend to be mentally quick older adults. Physical exercise not only enhances muscles, bones, and energy and helps prevent obesity and heart disease, it maintains the telomeres that protect the chromosome ends and even appears to slow the progression of Alzheimer’s disease.

Humans share an irresistible urge to organize our worlds into simple categories. Immediately after your birth (or before), everyone wanted to know, “Boy or girl?” Your parents may have offered clues with pink or blue clothing. The answer describes your sex, your biological status defined by your chromosomes and anatomy. For most people, those biological traits help define their assigned gender, the socially influenced characteristics by which people define boy, girl, man, and woman. 

Simply said, your body defines your sex. Your mind defines your gender. But your mind’s understanding of gender arises from the interplay between your biology and your experiences. 

Nature may blur the biological line between males and females. Intersex individuals are born with unusual combinations of male and female chromosomes, hormones, and anatomy. For example, a genetic male may be born with normal male hormones and testes but no penis or a micropenis. Such individuals may struggle with their gender identity.

• Gender Role: a set of expected behaviors, attitudes, and traits for males and females.

  • Men go to work. Women keep house and raise children.

• Gender Identity is our sense of being male, female, or some combination of the two. In other words, how do you show the world your gender?

• Gender Typing: the acquisition of a traditional masculine or feminine role

  • How did you learn about what it means to be male or female?

• Androgyny: displaying both traditional masculine and feminine physiological characteristics → nonbinary

• Transgender: an umbrella term describing people whose gender identity or expression differs from that associated with their sex designated at birth

We express the direction of our sexual interest in our sexual orientation—which usually is our enduring sexual attraction toward members of our own sex (homosexual) or the other sex (heterosexual). Other variations include an attraction to both sexes (bisexual) or no sexual attraction at all (asexual). We experience our sexual orientation in our interests, thoughts, and fantasies. 

Due to the controversy surrounding differing sexual orientation, research has been done in regards to how it develops and have found the following:

• Sexual orientation as neither willfully chosen nor willfully changed. 

• There is no evidence that environmental influences determine sexual orientation.

• Evidence for biological influences includes the presence of same-sex attraction in many animal species, straight-gay differences in body and brain characteristics, higher rates of homosexuality in certain families and in identical twins, the effect of exposure to certain hormones during critical periods of prenatal development, and the fraternal birth-order effect. 

Once conscious, how did your mind grow? Developmental psychologist Jean Piaget spent his life searching for the answer. He studied children’s cognition—all the mental activities associated with thinking, knowing, remembering, and communicating. His interest in children’s cognitive development began in 1920, when he was in Paris developing questions for children’s intelligence tests. While administering the tests, Piaget became intrigued by children’s wrong answers, which were often strikingly similar among same-age children. Where others saw childish mistakes, Piaget saw intelligence at work. Such accidental discoveries are among the fruits of psychological science.

Piaget’s core idea was that our intellectual progression reflects an unceasing struggle to make sense of our experiences. To this end, the maturing brain builds schemas, concepts or mental molds into which we pour our experiences.

To explain how we use and adjust our schemas, Piaget proposed two more concepts. First, we assimilate new experiences—we interpret them in terms of our current understandings (schemas). Having a simple schema for dog, for example, a toddler may call all four-legged animals dogs. But as we interact with the world, we also adjust, or accommodate, our schemas to incorporate information provided by new experiences. Thus, the child soon learns that the original dog schema is too broad and accommodates by refining the category. By adulthood we have built countless schemas, ranging from cats and dogs to our concept of love.

In other words, assimilation is forcing a new experience to fit into an existing box, accommodation is altering the box to fit the new experience. 

As Piaget was forming his theory of cognitive development, Russian psychologist Lev Vygotsky was also studying how children think and learn. Where Piaget emphasized how the child’s mind grows through interaction with the physical environment, Vygotsky emphasized how the child’s mind grows through interaction with the social environment. By giving children new words and mentoring them, parents and teachers provide what we now call a temporary scaffold (a framework that offers children temporary support as they develop higher levels of thinking) from which children can step to higher levels of thinking.

• Theory of Mind: people’s ideas about their own and other’s mental states (feelings, perceptions, thoughts, etc.) and the behaviors these might predict

Also developed by Vygotsky, the "zone of proximal development" (ZPD) is a concept in educational psychology that describes the space between what a learner can do independently and what they can achieve with guidance from a more knowledgeable person, like a teacher or peer, essentially representing the ideal range of challenge where significant learning can occur.

To answer this question, researchers used different cohorts (groups of people sharing a common characteristic) and conducted either cross-sectional or longitudinal studies. 

Through these studies, researchers have concluded that crystallized intelligence (our accumulated knowledge and verbal skills) increases with age while fluid intelligence (our ability to reason speedily and abstractly) decreases with age. This can explain while elders have retained much of the information they have learned throughout their life, but as very set in their ways and resistant to new ideas. 

As the years pass, recall begins to decline, especially for meaningless information, but recognition memory remains strong. Crystallized intelligence increases with age while fluid intelligence peaks in our 20s and then starts to decline. “Terminal decline” describes the cognitive decline in the final few years of life. 

Neurocognitive disorders (NCDs), formerly called dementia in older adults, are marked by cognitive deficits. Alzheimer’s disease causes the deterioration of memory, then reasoning. 

Psychologist Jonathan Haidt believes that much of our morality is rooted in moral intuitions—“quick gut feelings, or affectively laden intuitions.” According to this intuitionist view, the mind makes moral judgments in much the same way that it makes aesthetic judgments—quickly and automatically. Feelings of disgust or of elation trigger moral reasoning, says Haidt.

Our moral thinking and feeling surely affect our moral talk. But sometimes talk is cheap and emotions are fleeting. Morality involves doing the right thing, and what we do also depends on social influences. A big part of moral development is the self-discipline needed to restrain one’s own impulses—to delay small gratifications now to enable bigger rewards later. Our capacity to delay gratification—to decline small rewards now for bigger rewards later—is basic to our future academic, vocational, and social success. 

Language is our spoken, written, or signed words and the ways we combine them to communicate meaning. Language serves a variety of purposes:

• Form bonds

• Promote cooperation

• Record history

• Represent complex ideas

Theories of Language Development:

• Noam Chomsky - Nativist Theory

  • Universal grammar

  • Believed we are naturally equipped with a “language acquisition device” that helps us acquire language easily and rapidly but if language acquisition does not occur by a certain time, it may be impossible

• B.F. Skinner - Behaviorist Theory

  • Believed we learned language through imitation & reinforcement

• Lev Vygotsky - Sociocultural Theory

  • Believed we learned language through social interaction

While we are not born with language skills, we slowly acquire them over time. In our first months, we experience receptive language, where we focus on those that are speaking to us and try to respond. 

At 4 months, we begin babbling - uttering sounds. At 10 months, the babbles sound more like our household’s language. By a year, we know words, and by 2, we can talk in simple two-word phrases (telegraphic speech). From there, our vocabulary rapidly develops. 

Childhood is a critical period for mastering certain aspects of language before the language-learning window gradually closes. Lack of exposure to either spoken or signed language by about age 7, can cause them to lose their ability to master any language. Children exposed to low-quality language—such as 4-year-olds in classrooms with 3-year-olds, or some children from impoverished homes—often display less language skill. We know this because of the case of “feral children” like Genie.

“Genie” was a teen girl discovered in Los Angeles in 1970 who became a crucial case study in linguistics and psychology. After being severely abused and isolated by her father, Genie had minimal human interaction and almost no exposure to language. Upon her discovery, Genie was malnourished and displayed developmental delays, was unable to speak beyond a few simple words and phrases, had a strange, bunny-like walk, and showed signs of profound psychological trauma. After her rescue, Genie became the subject of intense study by psychologists and linguists, particularly to understand the critical period hypothesis in language development—the idea that there is a window in early childhood when the human brain is particularly receptive to acquiring language.

As previously discussed, there are two specialized regions for language in the brain - Broca’s area & Wernicke’s area. If either of these is damaged, it cause cause aphasia - the impairment of language. 

• Broca’s Aphasia - difficulty with speech production and/or difficulty in putting words together in sentences or even speaking single words, although a person can sing a song

• Wernicke’s Aphasia - difficulty with language comprehension; may struggle putting words into meaningful sentences → word salad

Thinking and language - which comes first? Benjamin Lee Whorf proposed the idea of linguistic determinism - the theory that our language influences the nature of our thought and how we interpret the world around us. If your language doesn’t have a word for something, it is hard for you to think about it. The Hopi tribe do not have a past tense, thus they don’t think about the past. While we have only one word for snow, Eskimo have dozens of different words for snow. Additionally, multilingual speakers report having a different sense of self depending on the language they are using.

In a world without sound, language could develop through visual communication systems like sign language, relying on hand gestures, facial expressions, body movement, and spatial positioning to convey meaning, essentially utilizing the visual modality instead of the auditory one to express complex ideas and concepts.

We know that animals make sounds and use body language, but how else can they communicate?

Parents do matter. But parenting wields its largest effects at the extremes: the abused children who become abusive, the deeply loved but firmly handled who become self-confident and socially competent. As children mature, what other experiences do the work of nurturing? At all ages, but especially during childhood and adolescence, we seek to fit in with our groups.

• Family environment and parental expectations can affect children’s motivation and future success. Personality, however, is mostly not attributable to the effects of nurture.

• As children attempt to fit in with their peers, they tend to adopt their culture—habits, accents, and slang, for example.

• By choosing their children’s neighborhoods and schools, parents exert some influence over peer group culture.

Some parents spank, others reason. Some are strict, others are lax. Some show little affection, others liberally hug and kiss. How do parenting-style differences affect children? The most heavily researched aspect of parenting has been how, and to what extent, parents seek to control their children. Parenting styles can be described as a combination of two traits: how responsive and how demanding parents are. Investigators like Diana Baumrind have identified four parenting styles:

• Authoritarian parents are coercive. They impose rules and expect obedience.

  • “Don’t interrupt.” “Keep your room clean.” “Don’t stay out late or you’ll be grounded.” “Why? Because I said so.”

• Permissive parents are un-restraining. They make few demands, set few limits, and use little punishment.

• Negligent parents are uninvolved. They are neither demanding nor responsive. They are careless, inattentive, and do not seek to have a close relationship with their children.

• Authoritative parents are confrontive. They are both demanding and responsive. They exert control by setting rules, but, especially with older children, they encourage open discussion and allow exceptions.

Culture significantly impacts parenting styles by shaping a parent's beliefs about child-rearing, influencing the values they prioritize, and determining the practices considered appropriate for raising children within a specific community, including expectations regarding discipline, independence, respect for authority, and the role of family dynamics; essentially, how a parent was raised within their culture often informs how they parent their own children. 

Cultures that value individualism (personal goals are more important than communal goals) may encourage more independence and self-expression in children, while collectivist cultures (communal goals are more important than personal goals) may prioritize cooperation and group harmony, leading to different parenting approaches focused on social responsibility. 

Some cultures place a strong emphasis on respecting elders and authority figures, which can manifest in stricter parenting styles with more emphasis on obedience. 

Traditional gender roles within a culture can influence parenting styles, with mothers often taking on more nurturing roles and fathers assuming more disciplinary responsibilities. 

Cultures with a strong emphasis on academic achievement may push their children harder to excel in school, leading to different parenting approaches around study habits and extracurricular activities. 

Asian cultures are often associated with more authoritarian parenting styles focused on obedience, high academic expectations, and respect for elders. Western cultures may tend towards more permissive parenting with an emphasis on individual autonomy, self-expression, and open communication. Indigenous cultures may prioritize connection to nature, communal living, and collaborative decision-making in child-rearing practices.

One-year-olds typically cling tightly to a parent when they are frightened or expect separation. Reunited after being apart, they often shower the parent with smiles and hugs. This striking parent-infant attachment (an emotional tie with another person, shown in children by seeking closeness to their caregiver and showing distress on separation) bond is a powerful survival impulse that keeps infants close to their caregivers. Infants normally become attached to those—typically their parents—who they are comfortable and familiar with. 

Three key studies helped researchers understand the importance of attachment:

• Harry Harlow’s Monkey Experiment

• Konrad Lorenz’s Imprinting Geese

• Mary Ainsworth’s Strange Situation Procedure

In psychology, "temperament" refers to a person's natural disposition or characteristic behavioral style, including their typical mood, emotional reactivity, and how they generally respond to situations, essentially describing their "inner personality" that is largely considered to be present from birth and relatively stable over time; think of it as someone's innate tendency to react to the world in a particular way, like being naturally outgoing or reserved.

Developmental psychologist Erik Erikson believed that securely attached children approach life with a sense of basic trust—a sense that the world is predictable and reliable. He attributed basic trust not to environment or inborn temperament, but to early parenting. He theorized that infants blessed with sensitive, loving caregivers form a lifelong attitude of trust rather than fear. Therefore, infancy’s major social achievement is attachment.

Elements of Relationship Building:

• Parallel play: A stage of play commonly observed in toddlers, where children play alongside each other without directly interacting or engaging in cooperative play. They may be using similar toys or mimicking each other's actions but do not collaborate or share goals.

  • Example: Two toddlers sit side by side, each playing with their own set of building blocks. One child stacks blocks into a tower while the other lines them up in a row. They occasionally glance at each other but do not interact directly or share blocks.

• Pretend play: A type of play where children use their imagination to create scenarios, roles, and stories, often involving symbolic use of objects (e.g., a stick as a sword or pretending to cook). Also called "make-believe play."

  • Example: A child pretends to be a doctor by using a toy stethoscope to "check" their stuffed animals' heartbeat. They might say, "Your teddy bear is sick, but I’ll fix him with this medicine!"

• Egocentrism: A cognitive limitation in young children, particularly during Piaget's preoperational stage (ages 2-7), where they are unable to take the perspective of others. They believe that everyone sees, thinks, and feels the same way they do.

  • Example: A 4-year-old is talking to their grandmother on the phone and says, "Look at my drawing!" The child doesn’t understand that the grandmother cannot see what they are showing because they assume everyone sees what they see.

• Imaginary audience (a.k.a. the spotlight effect or #maincharacterenergy): A phenomenon often observed during adolescence, where individuals believe that others are constantly watching, judging, or paying attention to them, even when this is not the case.

  • Example: A teenager gets a pimple and refuses to go to school, thinking, "Everyone will notice it and make fun of me," even though most people might not even notice or care.

• Personal fable: Another aspect of adolescent egocentrism, where individuals believe that their experiences, feelings, and challenges are unique and unlike anyone else's. This can lead to feelings of invincibility or being misunderstood.

  • Example: A 16-year-old drives recklessly, thinking, "I’m a great driver, so nothing bad will happen to me," even though they are aware of statistics about car accidents. Or a teenager going through heartbreak might think, "No one has ever loved someone as much as I loved them, and no one can understand how I feel." 

Erik Erikson contended that each stage of life has its own psychosocial task, a crisis that needs resolution. Young children wrestle with issues of trust, then autonomy (independence), then initiative. School-age children strive for competence, feeling able and productive. But for teenagers, the task is to synthesize past, present, and future possibilities into a clearer sense of self. Young adults mature and develop capacity for intimacy (the ability to form close loving relationships), while those in the later stages of adulthood look back on their life and wonder if things could be different. 

According to Erikson, each stage of life adds a new layer to our personality. 

• Stage One: Trust vs Mistrust - Is my world supportive or unpredictable? → attachment to caregiver

• Stage Two: Autonomy vs Shame & Doubt - Can I do things for myself or must I rely on others? → potty training

• Stage Three: Initiative vs Guilt - Am I good or bad? → preschool

• Stage Four: Competence vs. Inferiority - Am I capable of success? → elementary school

• Stage Five: Identity vs Role Confusion - Who am I? → high school

• Stage Six: Intimacy vs Isolation - Will I go through my life alone or share it with others? → college, independence, marriage, children

• Stage Seven: Generativity vs Stagnation - What do I want to do before I die? → middle adulthood, possibly midlife crisis

• Stage Eight: Integrity vs Despair - Have I lived a good life? → retirement

Childhood’s major social achievement is a positive sense of self. By the end of childhood, at about age 12, most children have developed a self-concept—an understanding and assessment of who they are. Their self-esteem is how they feel about who they are. Children’s views of themselves affect their actions. Children who form a positive self-concept are more confident, independent, optimistic, assertive, and sociable.

Although teens become independent of their parents as they grow older, they nevertheless relate to their parents on a number of things, including religion and career choices. For a some parents and their adolescents, differences lead to real splits and great stress. But most disagreements are at the level of harmless bickering. With sons, the issues often are behavior problems, such as acting out or hygiene; for daughters, the issues commonly involve relationships, such as dating and friendships. 

Peer approval and relationships are also very important. Adolescence is typically a time of diminishing parental influence and growing peer influence. As they are finding their identity, they want to fit in, and this requires peer approval.

To refine their sense of identity, adolescents in individualist cultures usually try out different “selves” in different situations. They may act out one self at home, another with friends, and still another at school or online. If two situations overlap—as when a teenager brings new friends home—the discomfort can be considerable.. The teen often wonders, “Which self should I be? Which is the real me?” The eventual resolution is a self-definition that unifies the various selves into a consistent and comfortable sense of who one is—an identity. 

According to James Marcia, the presence or absence of a sense of commitment and a sense of crisis can combine to form four different identity statuses:

• Identity diffusion is a state of apathy with no commitment to an ideology

• Identity foreclosure is a premature commitment to visions, values, and goals

• Identity moratorium involves delaying commitment for a while to experiment with alternative ideologies and careers

• Identity achievement is arriving at one’s sense of self and direction after thinking through alternatives

Other influences on one's identity include:

• Race/Ethnicity

  • Provides a sense of belonging and pride in one's heritage.

  • Influences experiences of discrimination, privilege, or marginalization, shaping self-concept.

  • Plays a role in cultural practices, traditions, and shared language, which contribute to one's worldview.

• Gender

  • Influences self-expression, roles, and expectations based on societal norms and personal beliefs.

  • Challenges to traditional gender roles can foster self-exploration and authenticity.

  • Social support and acceptance of one’s gender identity can strengthen self-esteem, while societal pressure or discrimination may create conflict.

• Sexuality

  • Shapes personal relationships, intimacy, and connections with others.

  • Coming out or affirming one’s sexual identity can be a significant step in forming an authentic self.

  • Societal acceptance or stigma surrounding sexual orientation can influence mental health and self-perception.

• Religion

  • Provides a moral framework, guiding principles, and a sense of purpose while offering a community of belonging and support.

  • Influences worldview, decision-making, and coping strategies.

  • For some, struggles with faith or changes in religious identity can prompt significant self-reflection and growth.

• Occupation

  • Represents a source of self-esteem and achievement.

  • Shapes social roles and interactions, as people often define themselves by what they do.

  • Challenges, such as unemployment or career changes, can impact self-concept and lead to identity exploration.

  • Work-life balance and job satisfaction contribute to overall identity stability.

• Family

  • Early family dynamics play a critical role in developing self-concept and attachment styles.

  • Family traditions, values, and expectations contribute to one’s understanding of themselves and their place in the world.

  • Conflict or harmony within the family can shape one’s ability to form healthy relationships.

Learning is the process of acquiring through experience new and relatively enduring information or behaviors. As humans, we have to learn to adapt to our environments- knowing when to expect pain, knowing how to act in certain social situations, knowing what behaviors will be rewarded and which will be punished, etc. Both humans and animals learn through association or associative learning - realizing that certain events occur together. 

Dr. Ivan Pavlov was a physician studying digestion in dogs who noticed that these dogs would start drooling at the sight of his lab assistants, despite the absence of food. Because they associated food with these assistants, the dogs knew food was coming and responded accordingly. Pavlov found this curious and decided to change his experiments to test the theory of what he called “psychic reflexes”.

Dogs were harnessed and equipped with a mechanism to collect saliva, then presented with a neutral external stimulus (bell/tone), followed immediately by the unconditioned stimulus (food/meat powder). After several repetitions, the dogs were presented with the external stimulus without the unconditioned stimulus to see if there was a response. If there was, the neutral stimulus has become a conditioned stimulus, and their reaction is a conditioned response. 

His work and findings became the basis for classical conditioning - a type of passive learning in which we link two or more stimuli. It also encouraged the growth of behaviorism - the view that psychology should be an objective science that studies observable actions without reference to internal mental processes. 

• Unconditioned Stimulus (US): unlearned, naturally occurring cause of behavior

• Neutral Stimulus (NS): elicits no response before conditioning

• Unconditioned Response (UR): unlearned, naturally occurring behavior

• Conditioned Stimulus (CS): learned cause of behavior

• Conditioned Response (CR): learned behavior

John B. Watson, a behaviorist, wanted to study if specific fears could be conditioned. In his experiment, Watson took the infant child of his graduate student nicknamed “Little Albert” and placed a white rat in his lap. Like most infants, Albert was amused by the creature. Watson then took it away, and when Little Albert reached for it, Watson struck a hammer against a steel bar, creating a loud noise that scared Little Albert (as it would most infants), who burst into tears. After a few rounds of this, Little Albert would cry at the sight of the rat, but also all things white and fuzzy - rabbits, dogs, coats, even Santa Claus. This experiment proved that fear can indeed be conditioned. This type of classical conditioning is also known as aversive conditioning.

More than the early behaviorists realized, an animal’s capacity for conditioning is limited by biological constraints. For example, each species’ predispositions prepare it to learn the associations that enhance its survival—a phenomenon called preparedness. Environments are not the whole story. Biology matters.

John Garcia was among those who challenged the prevailing idea that all associations can be learned equally well. While researching the effects of radiation on laboratory animals, Garcia and Robert Koelling noticed that rats began to avoid drinking water from the plastic bottles in radiation chambers because it made them sick. Their findings came to be known as taste aversion - when exposed to the sight or smell of something that is associated with nausea or vomiting, one feels ill and is unlikely to expose themselves to it again.

Operant conditioning is a type of learning in which a behavior becomes more likely to recur if followed by a reinforcer or less likely to recur if followed by a punisher.

This is based on Edward Thorndike’s law of effect - the principle that behaviors followed by favorable consequences become more likely, and behaviors followed by unfavorable consequences become less likely.

Burrhus Frederic Skinner, the “Father of Behaviorism” or “Father of Operant Conditioning”, elaborated on the law of effect, studying how pigeons and rats learn through reinforcement.  

He crafted an operant chamber, or Skinner box, which contained a bar or key that an animal can manipulate to obtain food or water. 

In operant conditioning, reinforcement is any event that strengthens (or increases the likelihood) the behavior that follows.

• positive reinforcement: increasing behaviors by presenting rewarding stimuli

  • Getting good grades encourages you to study, getting complimented on your looks encourages you to dress a certain way

• negative reinforcement: increasing behaviors by stopping or reducing aversive stimuli

  • Putting on a coat to stop feeling cold, cleaning your room to get rid of the mess/smell

  • NOT THE SAME AS PUNISHMENT

• Primary Reinforcers are innately rewarding by satisfying a biological need (food, water, shelter, etc.).

• Conditioned (Secondary) Reinforcers are those that gain power through association with a primary reinforcer (money to buy food, water, shelter, etc.).

• Reinforcement Schedules are patterns that define how often a desired response will be reinforced.

• Continuous reinforcement - the desired behavior is reinforced every time

  • • Used in the acquisition stage

    • Learning occurs faster, but doesn’t last as long

• Partial or intermittent reinforcement - the desired behavior is reinforced only some of the time

  • • Used once behavior is mastered

    • Learning occurs slowly, but lasts longer

• Token economy: a system in which the learner earns tokens by engaging in a targeted behavior and those tokens can be exchanged for a reward.

Fixed means a set number, variable means a random or changing number. Interval requires time to pass, ratio requires actions to be taken.

• Fixed ratio - a reinforcement schedule that reinforces a desired behavior only after a specific number of actions have been completed (ex. Getting a bonus for every three cars sold)

• Fixed interval - a reinforcement schedule that reinforces a desired behavior only after a specific amount of time has passed (ex. Getting a paycheck every week)

• Variable ratio - a reinforcement schedule that reinforces a desired behavior only after a specific number of actions have been completed (ex. Slot machines)

• Variable interval - a reinforcement schedule that reinforces a desired behavior only after a unpredictable amount of time has passed (ex. Cooking times)

Reinforcement increases the likelihood that a response will happen, while punishment decreases it. Punishment is any event that tends to decrease the behavior that it follows.

• Positive punishment - administration of an aversive stimulus

  • • Traffic tickets, given extra chores

• Negative punishment - removal of a pleasant/rewarding stimulus

  • • Fines (losing money), losing car/phone privileges, getting grounded (losing freedom)

Shaping is the process in which reinforcers guide behavior toward closer and closer (successive approximations) to the desired behavior (a.k.a. training).

For example, we you teach a puppy to sit, first they get a treat just for coming to you when called. When that is mastered, they get a treat for standing still. Finally, after a few times repeating the word “sit” and pushing their bottom down, they finally master the desired behavior of sitting when told to do so. 

To signal a response will be reinforced, discriminative stimuli (a stimulus that elicits a response after association with reinforcement) are often used in the shaping process. In later versions of Skinner’s operant chambers, an electrified grid was added to elicit a light shock to the animals as an aversive stimulus. To warn the rats of the impending shock, a tone or light would come on. The shock would stop if a button was pressed. Soon the rats learned to press the button as soon as the light came on to avoid the shock. 

• Escape learning: a type of negative reinforcement in which a behavior that removes an unpleasant stimulus is increased

  • • Faking sick to leave a social gathering, sneaking out the back of the restaurant to get away from a bad date

• Avoidance learning: a type of negative reinforcement in which a behavior that prevents removes an unpleasant stimulus is increased

  • • Claiming your parents won’t allow you to attend the social gathering, ghosting people you are not interested in

Beyond instinct, we cannot dismiss all cognition from the learning process, as there is evidence that mental processes play a huge role in acquisition of knowledge.

• • • Latent learning: learning that occurs but is not apparent until there is an incentive to demonstrate it → Edward Tolman’s Maze Study

      • Cognitive map - a mental representation of the layout of one’s environment

      • If you were blindfolded, you could easily navigate through your home. You never studied the blueprints, but you know the layout of your house. 

    • Insight learning: a sudden realization of a problem’s solution

Observational learning is the acquisition of knowledge through watching others. Children often mimic the actions of their family members and peers, who act as models. Modeling is the process of observing and imitating a specific behavior. This process is accomplished through the use of mirror neurons, which fire when we observe an action and/or attempt to perform it. This is how we learn to perform certain tasks, but also how we learn things like empathy.

To test the effectiveness of observational learning, Albert Bandura devised an experiment in which children watched adults play with various toys in a room, one of which was an inflatable clown doll named Bobo. If the children witnessed the adults playing nicely with Bobo, they would do so when they entered the toy room. If the children witnessed the adults beating, kicking, and mistreating Bobo, they would mimic those actions as well. Bandura’s studies proved that much of the behavior we learn, good and bad, is learned through observation and imitation.

The good news is that people’s modeling of prosocial (positive, helpful) behaviors can have prosocial effects. Many business organizations effectively use behavior modeling to help new employees learn communications, sales, and customer service skills. Trainees gain these skills faster when they are able to observe the skills being modeled effectively by experienced workers (or actors simulating them).

The bad news is that observational learning may also have antisocial effects. This helps us understand why abusive parents might have aggressive children, why children who are lied to become more likely to cheat and lie, and why many men who beat their wives had wife-battering fathers. Critics note that such aggressiveness could be genetic. But with monkeys, we know it can be environmental. In study after study, young monkeys separated from their mothers and subjected to high levels of aggression grew up to be aggressive themselves. The lessons we learn as children are not easily replaced as adults, and they are sometimes visited on future generations.