Developmental Theories (Piaget, Erikson)
A high-yield Step 1 behavioral-science lesson pairing Piaget's 4 cognitive stages with Erikson's 8 psychosocial stages, built around exam buzzwords (object permanence, conservation, egocentrism, identity vs. role confusion) and age-anchored vignette pattern recognition.
Why this shows up on Step 1
Developmental milestones are a Step 1 favorite because a single normal behavior can be turned into a question: name the stage, predict the next skill, or decide whether the child is delayed. Two frameworks dominate. Piaget describes cognitive development — how a child thinks — across 4 stages (birth to adolescence). Erikson describes psychosocial development — the emotional conflict to resolve — across 8 stages spanning the entire lifespan.
Vignettes almost never name the theorist. They hand you an age + a behavior (a toddler who hides by covering only their own eyes; a teenager 'trying on' identities; a retiree reviewing their life) and expect you to map it to the stage. Master the age ranges and the one buzzword behavior per stage, and most of these questions collapse into pattern recognition. The classic distractor is treating a normal age-appropriate behavior as pathology — the answer is usually reassurance, not a workup.
- Sensorimotor (birth–2 yr): learns through senses/movement. Milestone = object permanence (~9 mo) — searches for a hidden toy. Stranger anxiety emerges in this age range.
- Preoperational (2–7 yr): symbolic/pretend play + egocentrism (cannot take another's viewpoint); magical thinking, animism; lacks conservation (says a tall thin glass holds more than a short wide one of equal volume).
- Concrete operational (7–11 yr): achieves conservation and reversibility; logical about concrete/tangible things; can classify and seriate — but cannot reason abstractly.
- Formal operational (≥11–12 yr): abstract + hypothetical reasoning, deductive 'if–then' logic. Not everyone fully reaches it.
Highest-yield discriminators:
- Egocentrism = preoperational
- Conservation absent → preoperational; present → concrete operational
- Abstract/hypothetical thought = formal operational
Erikson — the 8 psychosocial stages
| Approx age | Conflict | Virtue (if resolved) | Classic vignette cue |
|---|---|---|---|
| 0–18 mo (infant) | Trust vs. Mistrust | Hope | Depends on caregiver reliability/feeding |
| 18 mo–3 yr (toddler) | Autonomy vs. Shame & Doubt | Will | Toilet training, 'No!', 'I do it!' |
| 3–6 yr (preschool) | Initiative vs. Guilt | Purpose | Initiates play, asks endless questions |
| 6–11 yr (school age) | Industry vs. Inferiority | Competence | Schoolwork, comparing self to peers |
| 12–18 yr (adolescent) | Identity vs. Role Confusion | Fidelity | 'Trying on' identities, groups, styles |
| 18–40 yr (young adult) | Intimacy vs. Isolation | Love | Committed intimate relationships |
| 40–65 yr (middle adult) | Generativity vs. Stagnation | Care | Mentoring, raising family, legacy |
| 65+ yr (older adult) | Integrity vs. Despair | Wisdom | Life review: acceptance vs. regret |
Vignette 1: A 10-month-old watches you hide a rattle under a blanket and immediately pulls the blanket off to grab it. → Object permanence intact = sensorimotor. Normal for age. Next step: reassure.
Vignette 2: A 4-year-old insists the taller of two identical-volume glasses 'has more juice,' and when asked to draw what a friend across the table sees, she draws her own view. → Lacks conservation + egocentrism = preoperational. Normal, not delayed.
Vignette 3: A 9-year-old correctly states the amount of clay is unchanged after a ball is rolled into a snake, but struggles with a purely hypothetical 'what if the sky were green?' problem. → Concrete operational — conservation present, abstract reasoning not yet expected.
Vignette 4: A 14-year-old debates a hypothetical ethics scenario and reasons through 'if–then' consequences. → Formal operational.
Board pattern: when the behavior matches the age, the answer is normal development / reassurance, not imaging or labs.
Vignette 1: A healthy 2-year-old refuses help dressing, shouts 'I do it!', and resists toilet training. → Autonomy vs. Shame & Doubt. Guidance: encourage safe independence (offer choices), avoid shaming.
Vignette 2: A 15-year-old repeatedly changes friend groups, music, and clothing and asks 'who am I really?' → Identity vs. Role Confusion — normal adolescent identity formation, not a mood or conduct disorder.
Vignette 3: A 45-year-old with career success feels empty because he 'hasn't given anything back' or contributed to the next generation. → struggling with Generativity vs. Stagnation.
Vignette 4: A 78-year-old with terminal cancer reflects calmly, feeling his life had meaning. → successful Integrity vs. Despair (pervasive regret/hopelessness would signal despair).
Trap: don't label age-appropriate psychosocial behavior (toddler defiance, teen identity searching) as a psychiatric diagnosis.
Piaget's 4 stages in order — 'Some People Can Fly':
- Sensorimotor → Preoperational → Concrete operational → Formal operational
Piaget age anchor — 2 · 7 · 11: Sensorimotor birth–2, Preoperational 2–7, Concrete 7–11, Formal 11+.
Erikson virtues in order (the 'gift' of each resolved stage): Hope, Will, Purpose, Competence, Fidelity, Love, Care, Wisdom. No universally standard acronym exists — instead anchor each stage to its life event:
- Toilet training → Autonomy
- Starting school → Industry
- Adolescence → Identity
- Retirement / life review → Integrity
One-line separator: Piaget = how you THINK (cognition); Erikson = how you FEEL/RELATE (psychosocial).
- Keep the vocab separate: Piaget = cognitive (thinking); Erikson = psychosocial (emotion/relationships). Mixing terms is the classic wrong answer.
- Egocentrism ≠ selfishness — it is the cognitive inability to take another's perspective (preoperational), not a moral failing.
- Conservation is the single highest-yield Piaget discriminator: absent = preoperational, present = concrete operational.
- Stranger anxiety (~6 mo) and separation anxiety (~9 mo, peaks 12–18 mo, normal to ~2–3 yr) are developmentally normal (Erikson trust/autonomy era) → reassure.
- Object permanence ~9 mo; its isolated absence at 8–9 mo is fine — only worry with other delays.
- Erikson stages are not rigidly age-locked (adults can revisit conflicts), but boards expect the canonical age → conflict pairing.
- Don't confuse frameworks with Freud (psychosexual: oral/anal/phallic/latency/genital) or Kohlberg (moral reasoning) — different axis, sometimes a distractor.
Piaget vs. Erikson — aligned by age
| Approx age | Piaget (cognitive) | Erikson (psychosocial) |
|---|---|---|
| 0–2 yr | Sensorimotor | Trust vs. Mistrust → Autonomy begins |
| 2–7 yr | Preoperational | Autonomy → Initiative |
| 7–11 yr | Concrete operational | Industry vs. Inferiority |
| 11–18 yr | Formal operational | Identity vs. Role Confusion |
| Young–middle adult | Formal operational (stable) | Intimacy → Generativity |
| Older adult | Formal operational (stable) | Integrity vs. Despair |
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