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Human development isn't just a timeline of birthdays—it's the foundation for understanding why people think, feel, and behave the way they do at different points in life. On the AP Psychology exam, you're being tested on your ability to connect developmental milestones to the theories that explain them: Piaget's cognitive stages, attachment theory, Erikson's psychosocial conflicts, and Vygotsky's sociocultural approach. The exam loves asking you to identify which stage a child is in based on their behavior, or to explain why early experiences create lasting psychological effects.
The key insight here is that development isn't random—it follows predictable patterns shaped by biological maturation, social interaction, and environmental factors. Whether you're analyzing why a toddler fails a conservation task or explaining how adolescent brain development affects risk-taking, you need to understand the mechanisms behind each stage. Don't just memorize ages and stage names—know what cognitive, social, or emotional milestone defines each period and which theorist explains it best.
Cognitive development describes the progression from simple sensory experiences to abstract reasoning. Piaget proposed that children actively construct knowledge through interaction with their environment, moving through qualitatively different stages of thinking.
Compare: Preoperational vs. Concrete Operational—both involve logical limitations, but preoperational children fail conservation tasks due to centration, while concrete operational children succeed with tangible objects but struggle with abstract hypotheticals. FRQ tip: If asked about a child who can sort objects by size but can't reason about "what if" scenarios, they're concrete operational.
Social-emotional development explains how we form relationships and develop a sense of self. Early attachment experiences create internal working models that shape relationships throughout life.
Compare: Attachment styles vs. Erikson's trust vs. mistrust—both address early caregiver relationships, but attachment theory focuses on behavioral patterns in relationships, while Erikson emphasizes the psychological resolution of feeling the world is safe and predictable. Both predict long-term relationship outcomes.
Erikson proposed that personality develops through eight psychosocial conflicts, each presenting a crisis that must be resolved for healthy development. Successful resolution builds psychological strengths; failure creates vulnerabilities.
Compare: Industry vs. inferiority and identity vs. role confusion—both involve self-concept development, but industry focuses on competence in specific skills, while identity involves integrating all aspects of self into a coherent whole. If an FRQ describes a child struggling with schoolwork feeling "dumb," that's industry vs. inferiority; a teen unsure of their values is identity vs. role confusion.
Vygotsky emphasized that cognitive development is fundamentally social—children learn through guided participation with more knowledgeable others rather than through independent exploration alone.
Compare: Piaget vs. Vygotsky—both are constructivist theories, but Piaget emphasized individual discovery while Vygotsky emphasized social guidance. Piaget saw development as driving learning; Vygotsky saw learning as driving development. Exam tip: If a question mentions teachers, tutors, or collaboration, think Vygotsky.
Development doesn't stop at adolescence—cognitive, social, and physical changes continue throughout adulthood, with both gains and declines.
Compare: Crystallized vs. fluid intelligence—crystallized stays stable because it relies on stored knowledge, while fluid declines because it depends on processing speed and working memory, which are affected by neural changes. This distinction is heavily tested—know which cognitive abilities decline and which are preserved.
| Concept | Best Examples |
|---|---|
| Piaget's Stages | Sensorimotor (object permanence), Preoperational (egocentrism, conservation), Concrete operational (reversibility), Formal operational (abstract reasoning) |
| Erikson's Conflicts | Trust vs. mistrust, Autonomy vs. shame, Industry vs. inferiority, Identity vs. role confusion |
| Attachment Theory | Secure attachment, Ainsworth's Strange Situation, Harlow's contact comfort studies |
| Vygotsky's Concepts | Zone of proximal development (ZPD), Scaffolding, Social learning |
| Cognitive Aging | Crystallized vs. fluid intelligence, Cognitive reserve, Working memory decline |
| Theory of Mind | False-belief tasks, Perspective-taking, Development around age 4 |
| Adolescent Development | Prefrontal cortex maturation, Identity formation, Risk-taking behavior |
| Prenatal Influences | Teratogens, Critical periods, Fetal alcohol spectrum disorder |
A 5-year-old insists that a tall, thin glass contains more juice than a short, wide glass with the same amount. Which Piagetian concept explains this error, and what stage is the child in?
Compare Piaget's and Vygotsky's views on the role of social interaction in cognitive development. How would each theorist explain a child learning to solve a puzzle?
Which two of Erikson's stages both involve developing a sense of competence, and how do they differ in focus?
An elderly adult performs well on vocabulary tests but struggles with novel problem-solving tasks. Using the concepts of crystallized and fluid intelligence, explain this pattern.
How would you distinguish between a securely attached infant and an anxious-ambivalent infant in Ainsworth's Strange Situation? What long-term outcomes does attachment research predict for each style?