Developmental Psychology: How We Grow and Change

Piaget's Cognitive Development

Jean Piaget (1896-1980) proposed four stages of cognitive development. Sensorimotor (0-2 years): object permanence, means-end behavior, deferred imitation. Preoperational (2-7): symbolic thought, egocentrism, centration, animism, lack of conservation. Concrete operational (7-11): conservation, reversibility, classification, seriation — logical thinking about concrete objects. Formal operational (11+): abstract reasoning, hypothetical-deductive thinking, propositional logic. Neo-Piagetian theories: Robbie Case's central conceptual structures, Kurt Fischer's skill theory — address limitations of Piaget's rigid stages. Vygotsky's alternative: Zone of Proximal Development (ZPD), scaffolding, social constructivism — development driven by social interaction, not just individual exploration. Information processing approach: continuous development of attention, memory, processing speed — no distinct stages.

Attachment Theory

John Bowlby (1907-1990): attachment as an evolved behavioral system for infant survival. Internal working models: mental representations of self and others formed through early caregiving experiences. Mary Ainsworth's Strange Situation (1970): classified attachment styles — Secure (60-65%): distressed by separation, comforted by reunion. Insecure-Avoidant (20%): minimal distress, ignores caregiver on return. Insecure-Ambivalent/Resistant (10-15%): intense distress, difficult to comfort. Disorganized (15%): contradictory behaviors, associated with abuse/neglect. Adult attachment (Hazan & Shaver, 1987): childhood patterns predict romantic relationship quality. Attachment across cultures: secure attachment most common universally, but proportions vary. Earned security: adults with difficult childhoods can develop secure attachment through reflection and therapy. Neuroscience: oxytocin, vasopressin, dopamine systems underlie attachment bonding.

Erikson's Psychosocial Stages

Erik Erikson (1902-1994): eight stages of psychosocial development spanning the entire lifespan. Trust vs. Mistrust (0-1): consistent caregiving builds basic trust. Autonomy vs. Shame/Doubt (1-3): exploration and independence. Initiative vs. Guilt (3-6): purposeful behavior and planning. Industry vs. Inferiority (6-12): mastery of skills, academic achievement. Identity vs. Role Confusion (12-18): "Who am I?" — exploring values, beliefs, goals. Intimacy vs. Isolation (young adulthood): deep relationships vs. loneliness. Generativity vs. Stagnation (middle adulthood): contributing to next generation. Integrity vs. Despair (late adulthood): life review — acceptance or regret. Identity status (Marcia): diffusion, foreclosure, moratorium, achievement. Emerging adulthood (Arnett): new stage between adolescence and adulthood (18-25) in industrialized societies.

Adolescent Brain and Lifespan

Adolescent brain development: prefrontal cortex (executive function) matures last — not fully developed until age 25. Limbic system (emotion, reward) matures earlier → imbalance explains risk-taking, sensation-seeking, emotional intensity. Synaptic pruning: "use it or lose it" — connections strengthen or weaken based on experience during adolescence. Myelination continues through 20s: faster neural transmission, improved cognitive control. Neuroplasticity across lifespan: the brain remains changeable throughout life, but critical/sensitive periods exist. Cognitive aging: processing speed peaks at ~20, vocabulary peaks at ~60-70, crystallized intelligence stable until late life. Successful aging: cognitive reserve (education, engagement) buffers against decline. Neurogenesis in adults: new neurons generated in hippocampus throughout life — exercise and learning promote it. Epigenetic aging: methylation clocks (Horvath) track biological age independent of chronological age. The developing science of wisdom: integration of cognitive, reflective, and affective capacities with age.

❓ Frequently Asked Questions

Jean Piaget (1896-1980) proposed four stages of cognitive development. Sensorimotor (0-2 years): object permanence, means-end behavior, deferred imitation. Preoperational (2-7): symbolic thought, egoc...

John Bowlby (1907-1990): attachment as an evolved behavioral system for infant survival. Internal working models: mental representations of self and others formed through early caregiving experiences....

Erik Erikson (1902-1994): eight stages of psychosocial development spanning the entire lifespan. Trust vs. Mistrust (0-1): consistent caregiving builds basic trust. Autonomy vs. Shame/Doubt (1-3): exp...

Adolescent brain development: prefrontal cortex (executive function) matures last — not fully developed until age 25. Limbic system (emotion, reward) matures earlier → imbalance explains risk-taking, ...

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