Stage theories vs continuous models
IB Psychology· Human development· 14 min read
1. Core concept
There are two ways to picture how development unfolds. Stage theories (e.g. Piaget) say children pass through distinct, qualitatively different stages in a fixed order, with thinking reorganised at each step through schema, assimilation and accommodation. Continuous models (e.g. Vygotsky's sociocultural theory) see development as gradual and socially supported: with the right help inside the zone of proximal development (ZPD), a child can do sooner what a stage theory says is impossible for their age. The debate is whether developmental change is step-like or smooth.
2. Key studies
IB Psychology answers must be supported by named studies. Learn these to cite as evidence:
Piaget and Inhelder (1956)
In the 'three-mountains task', preoperational children could not report the scene from another person's viewpoint, taken as evidence of egocentrism fixed by their developmental stage. — Classic evidence for a Piagetian stage limit — cognition bounded by the child's stage.
Nedospasova (1985)
With social scaffolding inside the ZPD, preschool children could overcome egocentric errors earlier than their Piagetian stage 'should' allow. — Evidence for a continuous, socially-driven model — the limit shifts with support, not just with age.
3. Evaluation (AO3)
Strength — the two models complement each other — Stage theories give a clear developmental map; continuous/sociocultural models explain the variation and the role of teaching that stages miss — together they describe development better than either alone.
Limitation — Piaget's tasks may underestimate children — Borke (1975) simplified the three-mountains task and found children as young as three could succeed, suggesting the 'egocentrism' was partly a task artefact — stage boundaries are fuzzier than Piaget claimed.
4. Scope
5. Common Pitfalls
Wrong move:
Explaining Piaget just by naming his four stages (sensorimotor → formal operational).
Why:
A frequently penalised misconception in IB Psychology exams.
Correct move:
Credit comes from the CORE CONCEPTS that drive the stages — schema, assimilation, accommodation, equilibration — and from evaluating stage-vs-continuous, not from listing stage names.
Going deeper
- Schema theoryPiaget's schema/assimilation and cognitive schema theory are related but distinct — the schema-theory card (COG_8) warns against confusing them.
- Sociocultural factors in developmentVygotsky's model is sociocultural — development as culturally-scaffolded — linking to sociocultural factors (HD_2).