Major Developmental Theories

Why This Matters

Developmental psychology is one of the most heavily tested areas on the AP Psychology exam, and understanding these theories isn't just about memorizing names and stages—it's about grasping the fundamental debate over what drives human development. You'll see questions asking you to apply these theories to scenarios, compare theorists' assumptions, and identify which approach best explains a given behavior. The exam loves to test whether you understand the difference between theories that emphasize biological maturation, cognitive construction, social learning, and environmental systems.

Each theory you'll encounter here represents a different answer to psychology's biggest questions: Is development driven by nature or nurture? Does it happen in universal stages or depend on context? Is the individual an active constructor of knowledge or a passive recipient of experience? Don't just memorize the stages—know what mechanism each theorist proposes and how that mechanism differs from competing explanations. That's what separates a 3 from a 5.

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Stage Theories: Development as Universal Progression

These theorists argue that development unfolds in predictable, sequential stages that all humans pass through. The key mechanism is internal—whether cognitive structures, psychosexual energy, or moral reasoning capacity—and the stages are universal across cultures.

Piaget's Theory of Cognitive Development

• Four stages of cognitive growth—sensorimotor (0-2), preoperational (2-7), concrete operational (7-11), and formal operational (11+)—each representing qualitatively different ways of thinking
• Schemas are mental frameworks that children build and modify through assimilation (fitting new info into existing schemas) and accommodation (changing schemas when new info doesn't fit)
• Children as active learners who construct knowledge through exploration, not passive recipients of information—this distinguishes Piaget from behaviorist approaches

Erikson's Psychosocial Development Theory

• Eight lifespan stages, each defined by a psychosocial crisis (e.g., trust vs. mistrust, identity vs. role confusion) that must be resolved for healthy development
• Social relationships drive development—unlike Freud's biological focus, Erikson emphasized how interactions with family, peers, and culture shape personality
• Development continues into adulthood—stages like generativity vs. stagnation (middle adulthood) and integrity vs. despair (late adulthood) extend beyond childhood

Freud's Psychosexual Development Theory

• Five stages centered on erogenous zones—oral, anal, phallic, latency, and genital—with pleasure-seeking energy (libido) shifting focus at each stage
• Fixation occurs when conflicts at a stage remain unresolved, supposedly influencing adult personality (e.g., oral fixation leading to dependency or smoking)
• Id, ego, and superego represent the unconscious drives, reality-oriented mediator, and internalized moral standards that develop across these stages

Kohlberg's Theory of Moral Development

• Three levels of moral reasoning—preconventional (self-interest), conventional (social approval/law), and postconventional (universal ethical principles)—each with two substages
• Moral development depends on cognitive development—you can't reason at higher levels without the cognitive capacity that Piaget described
• Justice-focused framework that emphasizes rights and fairness, though critics (notably Gilligan) argue it undervalues care-based moral reasoning

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Social-Contextual Theories: Development Through Interaction

These theorists emphasize that development happens between people, not just inside individuals. The key mechanism is social interaction—learning from others, internalizing cultural tools, and being shaped by environmental systems.

Vygotsky's Sociocultural Theory

• Zone of Proximal Development (ZPD) describes the gap between what a child can do alone and what they can achieve with guidance—this is where learning happens
• Scaffolding is the support provided by more knowledgeable others (parents, teachers, peers) that helps learners move through their ZPD
• Language as a cognitive tool—unlike Piaget, Vygotsky saw private speech (talking to oneself) as essential for cognitive development, not just a sign of egocentrism

Bandura's Social Learning Theory

• Observational learning occurs through attention, retention, reproduction, and motivation—we learn by watching models, not just through direct reinforcement
• Self-efficacy is your belief in your ability to succeed, which influences whether you'll attempt challenging tasks and persist through difficulty
• Reciprocal determinism describes how behavior, personal factors (cognition, beliefs), and environment continuously influence each other—rejecting one-way causation

Bronfenbrenner's Ecological Systems Theory

• Five nested environmental systems—microsystem (immediate environment), mesosystem (connections between microsystems), exosystem (indirect influences), macrosystem (cultural values), and chronosystem (changes over time)
• Development is context-dependent—the same child develops differently depending on their family, school, neighborhood, culture, and historical moment
• Systems interact dynamically—a parent's job loss (exosystem) affects family stress (microsystem), which affects the child's school performance (mesosystem connection)

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Attachment and Early Relationships

These approaches focus specifically on how early bonds with caregivers shape emotional development and future relationships. The key mechanism is the quality of the attachment relationship, which creates internal working models for all future social connections.

Bowlby's Attachment Theory

• Attachment is biologically based—infants are evolutionarily programmed to seek proximity to caregivers for survival, and caregivers are primed to respond
• Internal working models are mental representations of relationships formed in infancy that shape expectations for future relationships and self-worth
• Secure base describes how healthy attachment allows children to explore confidently, knowing they can return to their caregiver for comfort

Ainsworth's Strange Situation

• Experimental procedure involving separations and reunions with caregiver in an unfamiliar room, designed to activate the attachment system under mild stress
• Three primary attachment styles—secure (distressed at separation, comforted at reunion), insecure-avoidant (indifferent to both), and insecure-resistant/ambivalent (highly distressed, not easily comforted)
• Caregiver sensitivity predicts attachment—responsive, consistent caregiving produces secure attachment; inconsistent or rejecting caregiving produces insecure styles

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Biological Maturation: Nature Over Nurture

This perspective emphasizes that development is primarily driven by genetic programming and biological timetables, with environment playing a minimal role in the sequence or timing of developmental milestones.

Gesell's Maturational Theory

• Development follows a genetic blueprint—children develop in a predictable sequence determined by heredity, not experience or teaching
• Readiness concept suggests that pushing children before they're biologically ready is futile; development unfolds according to an internal clock
• Developmental norms were established by Gesell's extensive observations, creating age-based milestones still used in pediatric assessments today

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Quick Reference Table

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Self-Check Questions

1. Which two theorists both propose stage-based cognitive development but differ on whether development is primarily individual or social? What specific concepts distinguish their approaches?

2. A child watches an older sibling get praised for sharing and then starts sharing more often. Which theory best explains this, and what key concept is demonstrated?

3. Compare Freud's and Erikson's approaches to development: What do they share in structure, and how do they differ in what drives development through each stage?

4. An FRQ describes a 4-year-old who believes the moon follows her when she walks and cannot understand that her mother has a perspective different from her own. Which Piagetian stage and concepts explain this behavior?

5. How would Gesell and Vygotsky give different advice to a parent asking whether to start teaching their 3-year-old to read? What underlying assumptions about development explain their disagreement?