Piaget's stages of cognitive and language development

Key ideas

• Schema: a mental framework for understanding something.
• Assimilation: fitting new information into an existing schema.
• Accommodation: changing a schema when new information does not fit.
• Equilibration: the drive to balance the two. A mismatch (disequilibrium) pushes the child to accommodate, which drives development.
• Development is driven by maturation plus the child's own exploration; stages come in a fixed, universal order.

The four stages

Piaget's stages (Simply Psychology)

Language in Piaget's theory

For Piaget, thought comes first and language reflects it: a child can only use words for concepts they already understand. Early speech is often egocentric (talk to oneself that ignores the listener) and becomes socialised speech as egocentrism declines in the concrete operational stage. Language development therefore tracks the cognitive stages: symbolic thought in the preoperational stage makes words possible.

Evaluation

• Underestimates children: McGarrigle and Donaldson's 'naughty teddy' study found 62.5% of children conserved when a puppet accidentally rearranged counters, compared with 16% when the experimenter did it deliberately, so the standard task's wording may confuse children.
• Stages may not be fixed or universal: formal operations appear in only some adults and vary with culture and schooling.
• Underplays social influence and language (Vygotsky's criticism).
• Strength: huge practical application in education (discovery learning, readiness), and his tasks are replicable.
• Method: small samples, often his own children, and clinical interviews that are open to subjective interpretation.

Worked example

A 5-year-old says a tall thin glass has more juice than a short wide one after watching the same juice poured between them. Explain using Piaget.

1. The child is in the **preoperational** stage (2 to 7).
2. She shows **centration**: focusing on height only.
3. She cannot yet **conserve** (understand quantity stays the same despite changes in appearance) or reverse the pouring in her head.

Answer: Preoperational: centration and lack of conservation.

Check yourself

1. A child calls every four-legged animal 'dog', then learns cats are different and creates a new category. This is
   • assimilation
   • accommodation
   • conservation
   • egocentrism
   Show answer

   accommodation. Changing a schema to fit new information is accommodation.

2. Object permanence develops in which stage?
   • Preoperational
   • Concrete operational
   • Formal operational
   • Sensorimotor
   Show answer

   Sensorimotor. It develops in the first two years.

3. The three mountains task was used to show
   • object permanence
   • egocentrism
   • abstract reasoning
   • accommodation
   Show answer

   egocentrism. Preoperational children choose their own view, not the doll's.

4. Which ability first appears in the formal operational stage?
   • Conservation of number
   • Object permanence
   • Reasoning about hypothetical situations
   • Using words as symbols
   Show answer

   Reasoning about hypothetical situations. Abstract, hypothetical thought.

5. In the naughty teddy study, 62.5% conserved with the puppet and 16% without. What is the difference in percentage points? Give your answer to 1 decimal place.
   Show answer

   46.5 percentage points. 62.5 - 16 = 46.5.

6. What is Piaget's view of language and thought?
   • Language develops first and creates thought
   • Language and thought are unrelated
   • Thought develops first and language reflects it
   • Language is learned only through reinforcement
   Show answer

   Thought develops first and language reflects it. For Piaget, words follow understanding.

7. Explain one weakness of Piaget's theory of cognitive development.
   Show answer

   He underestimated children's abilities: when tasks were made more child-friendly, as in the naughty teddy study, many younger children could conserve, so the stage ages may be wrong.. Evidence and what it shows about the stages.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification, Issue 6 (November 2024, first assessment January 2026)
• OpenStax Psychology: 9.2 Lifespan theories (Piaget, Erikson)

Last updated 8 November 2026. Spotted a mistake? Tell us.