AP Psychology Unit 3 Notes: Developmental Psychology (From Conception Through Adulthood)

Prenatal and Newborn Development

Developmental psychology asks how and why people change across the lifespan—physically, cognitively, and socially. Before you can understand later learning and behavior, you need a clear picture of how development starts and what early experiences (and risks) can shape the brain and body.

Major prenatal stages

Prenatal development is typically described in three broad stages. The key idea is that early development is not just “getting bigger”—it’s a carefully timed sequence where different organs and brain structures become vulnerable or resilient at different points.

• Germinal stage (first couple of weeks after conception): The fertilized egg divides rapidly, becomes a blastocyst, and implants in the uterine wall. If implantation fails, the pregnancy often ends before a person even knows they’re pregnant.
• Embryonic stage (roughly weeks 2–8): Major organs begin forming and the body plan develops. This is a high-risk period because organ systems are being built.
• Fetal stage (roughly week 9 to birth): The fetus grows dramatically in size, and many systems (especially the brain) continue maturing.

A helpful way to think about these stages is “construction vs. expansion”: the embryonic period is more like constructing the basic structure; the fetal period is more like expanding, refining, and wiring the system.

Teratogens and prenatal risk

A teratogen is any substance or environmental factor that can harm prenatal development. Teratogens matter because they help explain why two children with similar genetics can have very different outcomes—prenatal environments can change developmental trajectories.

Teratogen effects depend on:

1. Dose (how much exposure)
2. Timing (what is developing at that moment)
3. Genetic vulnerability (some fetuses are more susceptible)

Common examples emphasized in AP Psychology:

• Alcohol: Heavy prenatal alcohol exposure can lead to fetal alcohol syndrome (FAS), which can include growth problems and brain-based impairments. A common misconception is that only “severe alcoholism” matters; risk rises with greater exposure, and timing can affect which systems are most impacted.
• Nicotine (including smoking during pregnancy): Associated with increased risk of low birth weight and other complications.
• Infectious diseases: Some maternal infections can affect fetal development, especially at sensitive times.

Be careful with oversimplified cause-and-effect thinking: teratogens increase risk; they do not guarantee an outcome. Many exam questions test whether you understand that timing and vulnerability matter.

Newborn abilities: reflexes, senses, and preferences

Newborns arrive with built-in survival tools and learning-ready brains.

• Reflexes are automatic responses. Classic examples include the rooting reflex (turning toward touch on the cheek) and sucking reflex (sucking when something touches the lips). These matter because they show that some behaviors are “prewired,” not learned from scratch.
• Newborns also have functioning sensory systems, though they are not equally mature. Vision is relatively less sharp than hearing at birth, but infants quickly show preferences (for example, attending to high-contrast patterns and human faces).

A useful way to frame newborn development is: “prepared, not finished.” Babies are not miniature adults, but they are also not blank slates.

Temperament and early individual differences

Temperament refers to biologically influenced differences in emotional reactivity and self-regulation that appear early in life. Some infants are more easygoing; others react more intensely to stimulation or change. Temperament matters because it interacts with parenting and environment—development is often a “fit” between the child’s style and the demands/supports around them.

A common misconception is that temperament locks in destiny. Temperament shows early tendencies, but caregiving, culture, and experience shape how those tendencies play out.

Exam Focus

• Typical question patterns:
  • Identify which prenatal stage is most associated with organ formation vs. growth/maturation.
  • Apply the concept of a teratogen to a scenario (e.g., substance exposure) and predict likely risks.
  • Recognize newborn reflexes and explain why they are adaptive.
• Common mistakes:
  • Treating teratogen effects as guaranteed outcomes rather than risk factors influenced by timing and dose.
  • Confusing reflexes (automatic) with learned behaviors.
  • Assuming newborns have “no abilities” until they are taught—many capacities are present very early.

Cognitive Development (Piaget, Vygotsky)

Cognitive development is about how thinking changes—how you perceive the world, solve problems, use language, and reason. In AP Psychology, two major frameworks are Piaget’s stage theory (emphasizing self-driven discovery and universal stages) and Vygotsky’s sociocultural theory (emphasizing learning through social interaction and culture).

Piaget: schemas, assimilation, accommodation

Piaget argued that children actively build knowledge by interacting with the world. The building blocks of thought are schemas—mental frameworks for organizing information (for example, a schema for “dog” or “bedtime routine”). When you encounter something new, you either:

• Assimilate: fit the new experience into an existing schema (calling a small dog a “dog” because it matches your dog schema).
• Accommodate: modify your schema or create a new one when the old one doesn’t fit (realizing a “cat” is not a “dog,” and creating a new category).

This matters because Piaget is explaining a mechanism for learning: cognitive growth is not just adding facts; it’s restructuring how you think.

A common misconception is to treat assimilation as “correct” and accommodation as “wrong.” Both are normal. Accommodation is often what drives major conceptual change.

Piaget’s stages of cognitive development

Piaget proposed that cognitive development unfolds through stages tied to qualitative changes in how children think.

Sensorimotor: object permanence

Object permanence is the understanding that objects continue to exist even when they cannot be seen. Piaget linked this to major changes in mental representation.

Example: A baby who searches for a hidden toy is showing more than curiosity—they’re showing the ability to hold an internal representation of “toy” in mind.

Preoperational: egocentrism and conservation errors

In the preoperational stage, children can use words and mental images, but their reasoning is not yet “operational” (not yet able to mentally manipulate information using logical rules).

• Egocentrism: difficulty seeing the world from someone else’s viewpoint. This is not selfishness; it’s a cognitive limitation.
• Conservation: understanding that quantity stays the same despite changes in shape (e.g., the same water in a taller glass).

Why children fail conservation tasks: they often centration (focus on one feature, like height) and struggle with reversibility (mentally reversing an action).

Concrete vs. formal operations

Concrete operational thinkers can reason well with tangible examples. Formal operational thinkers can reason about abstract concepts (justice, algebraic relationships, hypothetical scientific tests). On the exam, a typical trap is assuming “formal operations” means adults always reason perfectly. People can have the capacity for formal reasoning but still rely on intuitive or emotion-driven thinking in real life.

Vygotsky: sociocultural learning, ZPD, scaffolding

Vygotsky emphasized that cognitive development is shaped by culture and social interaction. Instead of seeing development as mainly independent discovery, Vygotsky argued that children learn through guided participation.

• Zone of proximal development (ZPD): the range between what you can do independently and what you can do with help.
• Scaffolding: temporary support that allows you to perform a task until you can do it alone (hints, modeling, leading questions, breaking a task into steps).

This matters because it highlights how instruction can accelerate learning: the “sweet spot” is not tasks that are too easy (no growth) or too hard (frustration), but tasks in the ZPD.

Example: A child can’t solve a puzzle alone, but with a parent saying, “Try the corner pieces first,” the child succeeds. Over time, the child internalizes that strategy.

Comparing Piaget and Vygotsky (and common misconceptions)

Piaget and Vygotsky aren’t simply “opposites.” They often describe different angles:

• Piaget: stages, self-initiated exploration, universal patterns.
• Vygotsky: continuous growth, cultural tools (especially language), learning through interaction.

A common student error is to treat Piaget as saying “environment doesn’t matter.” Piaget did believe children learn by interacting with the environment; he just emphasized internal cognitive construction and stage-like shifts.

Exam Focus

• Typical question patterns:
  • Match a child’s behavior to a Piagetian stage (e.g., conservation failure → preoperational).
  • Distinguish assimilation vs. accommodation in a short scenario.
  • Identify ZPD and scaffolding in teacher-child or parent-child examples.
• Common mistakes:
  • Confusing egocentrism with selfishness rather than perspective-taking limits.
  • Assuming reaching formal operational thinking means a person always uses perfect logic.
  • Describing scaffolding as “doing the task for the child” instead of providing temporary, fading support.

Social and Emotional Development (Erikson, Attachment)

Social and emotional development focuses on how you form relationships, manage emotions, and build identity. Two central AP Psychology frameworks are Erikson’s psychosocial stages (life-span social tasks) and attachment theory (early emotional bonds and their effects).

Erikson: psychosocial development across the lifespan

Erik Erikson proposed that development involves a series of psychosocial conflicts. Each stage has a central challenge; how you handle it influences later development. The key point is not that you “pass” or “fail” permanently, but that each stage leaves a psychological residue—strengths and vulnerabilities.

Here are the stages most commonly emphasized in AP Psychology:

Why this matters: Erikson gives you a vocabulary for connecting social demands to emotional development. For example, adolescence isn’t just puberty—it’s also identity exploration under social pressure.

A common misconception is that these stages are strict age cutoffs. In reality, they describe typical developmental focuses, and people can revisit issues later.

Attachment: building emotional bonds

Attachment is a deep emotional bond between an infant and caregiver. Attachment matters because it is linked to later social relationships, emotion regulation, and stress responses.

Attachment is not simply “the baby likes the parent.” It’s a behavioral system: when distressed, an attached infant seeks proximity and comfort from a preferred caregiver.

The Strange Situation and attachment styles

Mary Ainsworth studied attachment using the Strange Situation, a structured observation where a caregiver leaves and returns while the infant’s reactions are observed. From this, researchers described patterns such as:

• Secure attachment: infant uses caregiver as a secure base; may protest separation but is soothed upon reunion.
• Insecure-avoidant attachment: infant appears emotionally distant; may not seek much comfort on reunion.
• Insecure-resistant (ambivalent) attachment: infant is very distressed by separation and not easily soothed upon reunion (may seek and resist contact).
• Disorganized attachment (often included in broader discussions): inconsistent or confused behaviors, sometimes linked to frightening or chaotic caregiving environments.

It’s important not to overinterpret these categories as permanent labels. They describe patterns in a specific context and can change with caregiving stability and later experiences.

What shapes attachment?

Attachment is associated with:

• Caregiver sensitivity/responsiveness: consistently responding to needs tends to support secure attachment.
• Infant temperament and broader family context can also matter (stress, resources, support systems).

A classic misconception is that attachment is about “spoiling” the baby. Attachment research generally emphasizes that responsive care supports healthy regulation; it doesn’t mean never setting limits.

Contact comfort and the importance of warmth

Research with infant monkeys (often associated with Harry Harlow) highlighted contact comfort—the soothing value of soft touch. The takeaway for AP Psychology is not that food is irrelevant (it’s essential), but that warmth and comfort are powerful drivers of attachment behavior.

Emotional development: regulation and social referencing

As infants and toddlers develop, they increasingly learn emotion regulation—managing emotional arousal to meet situational demands. One tool is social referencing, when an infant looks to a caregiver’s emotional reaction to interpret an uncertain situation.

Example: A toddler approaches a strange toy and looks back at a parent. If the parent smiles, the toddler explores; if the parent looks alarmed, the toddler hesitates.

Exam Focus

• Typical question patterns:
  • Identify the Erikson stage suggested by a scenario (e.g., teen exploring values → identity vs. role confusion).
  • Interpret Strange Situation behaviors to classify attachment style.
  • Apply “secure base” or “contact comfort” to explain infant behavior.
• Common mistakes:
  • Treating attachment styles as fixed personality traits rather than relationship patterns.
  • Confusing “avoidant” attachment with independence or maturity; it reflects a pattern of minimizing bids for comfort.
  • Assuming Erikson’s stages are rigid and that missing one “ruins” later development.

Adolescent and Adult Development

Development doesn’t stop after childhood. AP Psychology emphasizes that adolescence includes major physical and cognitive changes, and adulthood involves both gains (expertise, emotional regulation) and losses (some processing speed, physical capacity). Many exam questions also target how stable traits are versus how people change over time.

Adolescence: puberty, brain, and cognition

Adolescence is the transition from childhood to adulthood, beginning with puberty—the period of sexual maturation. Puberty involves hormonal changes that drive growth spurts and the development of primary and secondary sex characteristics.

Psychologically, adolescence is also a period of:

• Identity development (strongly tied to Erikson’s identity vs. role confusion)
• Increasing capacity for abstract reasoning (often described with Piaget’s formal operations)
• Heightened sensitivity to peers and social evaluation

A key nuance: adolescents can often reason abstractly in calm situations, but decision-making can shift under emotion, stress, or peer influence. On exams, scenarios frequently contrast “knows the risk” with “still takes the risk.” That doesn’t mean teens can’t think; it means context matters.

Social transitions: peers, parents, and autonomy

Adolescents typically spend more time with peers and negotiate autonomy from caregivers. This is not simply rebellion; it’s practice for adult independence. Conflicts often increase over everyday issues (curfews, chores), while deeper values may remain similar.

Emerging adulthood and young adulthood

Many modern developmental psychologists describe emerging adulthood as a period (often late teens through twenties) characterized by identity exploration and gradual assumption of adult roles. Whether this stage is emphasized varies by culture and economic context.

Young adulthood often highlights Erikson’s intimacy vs. isolation: forming close friendships and romantic partnerships that involve commitment and mutual support.

Middle adulthood: work, family, and generativity

In middle adulthood, many people focus on building and maintaining careers, families, and community roles. Erikson described the central task as generativity vs. stagnation—contributing to the next generation through parenting, mentoring, productive work, or community engagement.

The big idea is contribution: generativity is not only having children; it’s investing in things that outlast you.

Late adulthood: aging, cognition, and well-being

Aging includes physical changes (reduced muscle mass, slower reaction time) and cognitive changes that are often misrepresented.

• Fluid intelligence: the ability to reason quickly and solve novel problems. It tends to decline with age.
• Crystallized intelligence: accumulated knowledge and verbal skills. It often remains stable longer and can improve across adulthood.

This distinction matters because it prevents a common misconception: “aging means global cognitive collapse.” Many older adults show strong vocabulary, expertise, and judgment even if speed declines.

Erikson’s final stage, integrity vs. despair, focuses on reflecting on life with acceptance versus regret.

Developmental themes that cut across the lifespan

AP Psychology often frames development using three “big debates”:

• Nature vs. nurture: genes and environment interact.
• Continuity vs. stages: some changes are gradual; others appear stage-like.
• Stability vs. change: some traits show consistency; experiences can still reshape behavior.

When you answer FRQ-style questions, explicitly connecting a scenario to one of these themes can make your explanation clearer and more complete.

Exam Focus

• Typical question patterns:
  • Apply Erikson’s adolescence/adulthood stages to short life scenarios.
  • Distinguish fluid vs. crystallized intelligence in aging examples.
  • Explain adolescent risk-taking using cognition plus social context (peer influence).
• Common mistakes:
  • Assuming adolescent decision-making is always irrational rather than context-sensitive.
  • Treating “puberty” as purely psychological (it’s biological maturation with psychological effects).
  • Overgeneralizing that aging uniformly reduces all cognitive abilities.

Moral Development (Kohlberg, Gilligan)

Moral development asks how people reason about right and wrong. A crucial point: moral reasoning is not identical to moral behavior. Someone might reason at a sophisticated level yet still act selfishly under pressure; someone else might follow rules for simple reasons yet behave kindly.

Kohlberg: levels and stages of moral reasoning

Lawrence Kohlberg proposed that moral reasoning develops in a sequence of stages, grouped into three broad levels. His theory focuses on the logic behind your judgment, not whether you choose a particular action.

How to think about the stages

• In preconventional reasoning, rules feel external: “I’ll get in trouble” or “What’s in it for me?”
• In conventional reasoning, morality is tied to social systems: “Good people do X” or “We need laws to function.”
• In postconventional reasoning, a person evaluates laws themselves: “A law can be unjust; principles like human rights can outweigh it.”

Example (classic dilemma style): If asked whether someone should steal a drug to save a life, Kohlberg isn’t scoring “steal” vs. “don’t steal.” He’s scoring the reasoning:

• Stage 1: “No, because you’ll go to jail.”
• Stage 3: “Yes, because a good spouse saves their partner.”
• Stage 5: “Yes, because the right to life outweighs property laws; laws should serve human welfare.”

A common mistake is to memorize stage numbers without listening to the logic. On the AP exam, the wording of the justification is usually the clue.

Critiques and limits of Kohlberg

Kohlberg’s theory has been criticized for emphasizing justice-based reasoning and for potential cultural bias—what counts as “advanced” reasoning may reflect particular cultural values about individual rights and law.

Also, higher-stage reasoning is not the norm in everyday decisions. Many adults rely heavily on conventional reasoning in real life.

Gilligan: care ethics and relationships

Carol Gilligan argued that some moral reasoning is better captured by an ethic of care—prioritizing relationships, empathy, and responsibility for others—rather than solely a justice-and-rights framework.

This isn’t simply “women use care, men use justice.” That oversimplification is a common misconception. Gilligan’s broader point is that moral reasoning can emphasize different values (care/connection vs. rights/rules), and a complete view of morality should take both seriously.

Example: In a dilemma about telling a hurtful truth, a justice-focused response might emphasize honesty and fairness, while a care-focused response might emphasize minimizing harm and preserving trust.

Connecting moral development to other developmental theories

Moral development doesn’t happen in isolation:

• Cognitive growth (like abstract reasoning) can support more complex moral thinking.
• Social experiences (peers, culture, parenting) influence which values you practice.
• Identity development in adolescence often includes forming moral and political values.

Seeing these connections helps with higher-level exam questions that ask you to apply multiple concepts to the same scenario.

Exam Focus

• Typical question patterns:
  • Identify Kohlberg’s stage/level based on a person’s justification (punishment, approval, law, rights, universal principles).
  • Compare Kohlberg’s justice orientation with Gilligan’s care orientation in a scenario.
  • Distinguish moral reasoning from moral behavior (someone can “know” the right reasoning and still not do it).
• Common mistakes:
  • Scoring the decision (steal vs. don’t steal) instead of the reasoning behind it.
  • Treating postconventional reasoning as “breaking laws whenever you want” rather than evaluating laws using ethical principles.
  • Reducing Gilligan’s critique to a stereotype instead of understanding it as a broadened view of moral reasoning.