🧠 Psychology · Developmental Psychology

Development tricks that make stages stick

Erikson, Piaget, attachment theory, and milestones — memorized.

🧒 Developmental

Memory tricks

Proven mnemonics — fast to learn, hard to forget.

Attachment Styles
Ainsworth: Secure, Anxious, Avoidant — SAA
Attachment Styles
Three primary attachment patterns based on caregiver responsiveness
Secure: explores freely, upset at separation, easily comforted. Anxious: clingy, very distressed, hard to soothe. Avoidant: indifferent to caregiver, suppresses attachment needs.
Secure
Explores freely, calmed by reunion
Anxious
Clingy, hard to soothe
Avoidant
Indifferent to caregiver
Object Permanence
Object permanence develops ~8 months: things exist when hidden
Object Permanence
Before 8 months, out of sight literally means out of mind
Infants under ~8 months won't search for a toy hidden under a blanket — they don't understand it still exists. After object permanence develops, they'll search for it.
Zone of Proximal Development
Vygotsky's ZPD: the gap between what you can do alone vs with help
Zone of Proximal Development
Learning happens best just beyond current ability with the right support
ZPD = what a learner can do with guidance but not yet alone. Scaffolding = teacher support that bridges this gap. Gradually remove support as competence grows.
Kohlberg's Moral Development
Kohlberg's 3 levels of moral development: Pre-conventional, Conventional, Post-conventional
Kohlberg's Moral Development
Three levels of moral reasoning — from self-interest to universal principles
Pre-conventional: morality based on consequences to self (punishment and reward). Conventional: morality based on social rules and laws. Post-conventional: morality based on universal ethical principles.
Prenatal Development Stages
Prenatal development: germinal (0-2 weeks) → embryonic (2-8 weeks, most vulnerable) → fetal (8 weeks-birth)
Prenatal Development Stages
Three stages from conception to birth
Germinal: fertilization through implantation (~2 weeks). Embryonic (2-8 weeks): major organs and structures form — most vulnerable to teratogens (alcohol, drugs, infections). Fetal (8 weeks to birth): growth and refinement of systems. Teratogens cause most damage during embryonic stage when organs are forming.
Infant Temperament
Temperament: easy, difficult, slow-to-warm-up — largely innate, influences parenting and development
Infant Temperament
Inborn differences in emotional reactivity and self-regulation
Thomas and Chess: Easy (40%): adaptable, positive mood, regular routines. Difficult (10%): intense reactions, slow to adapt, negative mood. Slow-to-warm-up (15%): initially withdraws, gradually adapts. Goodness of fit: match between child's temperament and parenting style predicts outcomes.
Parenting Styles
Authoritative parenting: high warmth + high control = best outcomes. Authoritarian: low warmth + high control.
Parenting Styles
Baumrind's four parenting styles and their outcomes
Authoritative: warm, responsive, consistent boundaries → children: confident, socially skilled, academically successful. Authoritarian: strict, low warmth, punitive → children: obedient but lower self-esteem. Permissive: warm but few rules → children: impulsive, lower achievement. Uninvolved: low warmth and low control → worst outcomes.
Authoritative
High warmth + high control — best outcomes
Authoritarian
Low warmth + high control — obedient but anxious
Permissive
High warmth + low control — impulsive
Uninvolved
Low warmth + low control — worst outcomes
Adolescent Development
Adolescence: identity formation (Erikson), formal operations (Piaget), puberty, peer influence peak
Adolescent Development
The key developmental tasks and changes of adolescence
Physical: puberty — hormonal changes, primary and secondary sex characteristics. Cognitive: formal operational thought — abstract reasoning, hypothetical thinking. Social: Erikson's identity vs role confusion — 'Who am I?' Peer influence peaks. Risk-taking increases — prefrontal cortex not fully developed until ~25.
Cognitive Aging
Aging: fluid intelligence (speed, working memory) declines. Crystallized intelligence (knowledge, vocabulary) maintained.
Cognitive Aging
How different types of intelligence change across the lifespan
Fluid intelligence: raw processing speed, working memory, novel problem-solving — peaks in 20s, declines gradually. Crystallized intelligence: accumulated knowledge, vocabulary, expertise — maintained or increases into old age. Successful aging: staying physically active, mentally engaged, and socially connected.
Infant Social Development
Stranger anxiety: ~8 months. Separation anxiety: peaks ~14 months. Both signal healthy attachment.
Infant Social Development
Two normal anxiety responses that signal healthy development
Stranger anxiety: distress at unfamiliar people — emerges ~6-8 months when infants can distinguish familiar from unfamiliar faces. Separation anxiety: distress when attachment figure leaves — peaks ~14 months, gradually decreases. Both signal that healthy attachment has formed. Absence may indicate attachment problems.
Theory of Mind
Theory of mind: understanding that others have different beliefs, desires, and knowledge than you do
Theory of Mind
The ability to understand other people's mental states
Develops around age 4. False belief task: child understands that another person can have a false belief. Before theory of mind: children assume everyone knows what they know (egocentrism). Autism spectrum disorder often involves theory of mind deficits. Foundation of empathy and social understanding.
Erikson's Stages
TIAPIGID — Trust, Initiative, Industry, Autonomy, Puberty, Intimacy, Generativity, Integrity, Despair
8 psychosocial crises across the full lifespan — each must be resolved
Erikson extended development across the entire lifespan — not just childhood
Stage 1 (0-1): Trust vs. Mistrust — reliable caregiving builds trust. Stage 2 (1-3): Autonomy vs. Shame — independence vs. doubt. Stage 3 (3-6): Initiative vs. Guilt — purpose vs. overrestriction. Stage 4 (6-12): Industry vs. Inferiority — competence vs. inadequacy. Stage 5 (12-18): Identity vs. Role Confusion — Erikson's signature stage. Stage 6 (young adult): Intimacy vs. Isolation. Stage 7 (middle): Generativity vs. Stagnation. Stage 8 (late): Integrity vs. Despair.
Identity (Stage 5)
Erikson's most influential — adolescent identity crisis
Generativity
Contributing to society and next generation
Integrity
Looking back with satisfaction vs. regret
Moral Development
PCP — Pre-conventional, Conventional, Post-conventional
Kohlberg's three levels of moral reasoning — each with two stages
Kohlberg extended Piaget's work — moral reasoning develops in stages tied to cognitive growth
Pre-conventional (childhood): Stage 1 — obedience to avoid punishment; Stage 2 — self-interest and exchange. Conventional (adolescence/adults): Stage 3 — good interpersonal relationships; Stage 4 — law and social order. Post-conventional (few adults): Stage 5 — social contract and individual rights; Stage 6 — universal ethical principles. Gilligan's critique: Kohlberg's model is male-biased — women use an ethics of care, not just justice.
Pre-conventional
Punishment and reward — self-centered reasoning
Conventional
Rules and social order — most adults stop here
Post-conventional
Abstract principles — justice and human rights
Language Acquisition
BWST — Babbling, Words, Short phrases, Telegraphic speech
Stages of language development in the first three years of life
Language follows a universal sequence — LAD vs. learning theory debate shapes how we explain it
0-6 months: cooing. 6-12 months: babbling (all languages, then narrows). 12 months: first words. 18-24 months: vocabulary explosion (word spurt). 2 years: two-word utterances. 2-3 years: telegraphic speech (content words, no grammar). Chomsky's Language Acquisition Device (LAD): innate grammar mechanism — universal grammar. Behaviorist view (Skinner): imitation and reinforcement. Critical period hypothesis: language learning impaired if delayed past puberty.
LAD
Chomsky — children are pre-wired for language grammar
Critical period
Language delayed past puberty is severely impaired
Telegraphic
"More milk" — content words, no function words
Adolescent Development
FIPSE — Formal operations, Identity, Peer focus, Storm and stress, Egocentrism
Five key features of adolescent psychological development
Adolescence is shaped by formal operational thinking, identity formation, and social-emotional changes
Piaget's formal operations: abstract and hypothetical thinking emerges. Erikson's identity vs. role confusion: who am I? Marcia's identity statuses: diffusion, foreclosure, moratorium, achievement. Peer relationships become paramount — peer pressure and conformity peak. Adolescent egocentrism (Elkind): imaginary audience (everyone's watching me) + personal fable (I'm unique and invincible). Prefrontal cortex not fully mature until mid-20s — explains risk-taking.
Imaginary audience
Belief that everyone is watching and judging you
Personal fable
I'm special and invincible — explains risk-taking
Marcia's statuses
Diffusion, Foreclosure, Moratorium, Achievement
🎓 Common Exam Questions
Q: What are Piaget's four stages and what cognitive ability defines each?
A: Sensorimotor (0-2 years): object permanence — understanding that objects exist even when out of sight. Preoperational (2-7): egocentrism and symbolic thinking, but lacks conservation (can't understand same amount in different shapes). Concrete Operational (7-12): conservation mastered, logical thinking about concrete objects, reversibility. Formal Operational (12+): abstract and hypothetical reasoning, systematic problem-solving. Vygotsky's critique: Piaget underestimates the role of social interaction and language in cognitive development.
Q: Compare and contrast Ainsworth's four attachment styles and their long-term effects.
A: Secure (60%): consistent sensitive caregiving → child explores freely, returns to caregiver, positive internal working model → better social competence, relationships, mental health in adulthood. Anxious-Ambivalent (15%): inconsistent caregiving → clingy, distressed, hard to soothe → adult anxious attachment, relationship anxiety. Avoidant (20%): consistently unresponsive caregiving → suppresses attachment needs → adult dismissing attachment, discomfort with intimacy. Disorganized (5%): frightening or abusive caregiving → no coherent strategy → highest risk for psychopathology, dissociation, borderline personality.
Q: Explain Vygotsky's key concepts and how they differ from Piaget's approach.
A: Zone of Proximal Development (ZPD): the gap between what a child can do alone and what they can do with guidance from a more skilled partner — where learning optimally occurs. Scaffolding: temporary support from more skilled partners that is gradually withdrawn as competence grows. Language is the primary tool of cognitive development — internalized self-talk becomes inner speech and guides thinking. Contrast with Piaget: Piaget saw development as internal and biologically driven; Vygotsky saw it as fundamentally social and cultural. Piaget: development leads learning; Vygotsky: learning leads development.
Q: What are the three parenting styles (Baumrind) and which is associated with best outcomes?
A: Authoritative: high warmth plus high demandingness — clear rules with explanation and emotional responsiveness. Associated with best outcomes: high self-esteem, academic achievement, social competence, lower rates of problem behavior. Authoritarian: low warmth plus high demandingness — strict rules without explanation, obedience required. Associated with: obedient but anxious children, lower self-esteem. Permissive: high warmth plus low demandingness — few rules or consequences. Associated with: impulsive, low self-control. Uninvolved/neglectful: low warmth plus low demandingness — associated with worst outcomes across all domains.
Q: What is adolescent brain development and how does it explain adolescent behavior?
A: The prefrontal cortex (PFC) — responsible for impulse control, planning, risk assessment, and emotional regulation — is not fully mature until the mid-20s. The limbic system (emotional reward center) matures earlier. This mismatch produces the adolescent pattern: heightened emotional reactivity and reward-seeking with immature executive control. Explains: risk-taking behavior, sensation-seeking, susceptibility to peer influence (especially in presence of peers, which activates reward circuits), emotional volatility, and poor long-term decision-making. Has policy implications for juvenile justice and age limits on various activities.