Piaget's Stages

Piaget's Stages of Intellectual Development

Piaget proposed that children pass through four universal, invariant stages of cognitive development — each characterised by qualitatively different ways of thinking, not merely more knowledge. The stages follow in a fixed sequence (though age of transition varies), with each stage building on the schemas constructed in the previous one.

Stage 1 — Sensorimotor (Birth to ~2 years)

Infants understand the world through sensory experience and motor action — there is initially no symbolic thought. Key achievements include: circular reactions (repeating actions that produce interesting effects); object permanence — the understanding that objects continue to exist when out of sight, which Piaget claimed develops around 8–9 months. Before this, the infant acts as if an object ceases to exist when hidden. The A-not-B error demonstrates this: an infant who repeatedly finds a toy at location A will still search there even after watching it hidden at location B — they search according to their action history, not the object's location.

Stage 2 — Pre-operational (approximately 2–7 years)

The child develops language and symbolic representation but lacks logical operations. Key limitations:

• Egocentrism: difficulty adopting another person's perspective. Piaget and Inhelder's three mountains task: children shown a 3D mountain display from one position chose a picture showing their own view rather than a doll's view from a different position — interpreted as inability to decenter from own perspective.
• Centration: focusing on only one aspect of a situation whilst ignoring others — key to failures of conservation.
• Lack of conservation: inability to understand that quantity does not change with irrelevant perceptual transformation. In the classic liquid conservation task, children under 7 say the taller, thinner glass has more liquid after the same liquid is poured into it.
• Animism: attributing life and intentions to inanimate objects (e.g. 'the sun is following me').
• Irreversibility: inability to mentally reverse a sequence of steps.

Stage 3 — Concrete Operational (approximately 7–11 years)

The child acquires logical operations but only for concrete, tangible objects — not for abstract propositions. Key achievements: conservation (supported by decentration and reversibility); class inclusion (e.g. understanding that there are more animals than dogs when shown a mixed set); seriation (ordering objects by a dimension such as size); reversibility (mentally undoing an action).

Stage 4 — Formal Operational (approximately 11+ years)

The adolescent can reason about abstract propositions, hypothetical possibilities, and systematic experimentation. Hypothetico-deductive reasoning: generating hypotheses and systematically testing them. Propositional thought: evaluating logical statements independently of their concrete referents. Piaget acknowledged that not all adults reach full formal operational thinking — it may depend on experience and cultural context.

Evaluation of the Stage Model

McGarrigle and Donaldson (1974) showed that Piaget's conservation tasks may underestimate children's abilities by using a 'naughty teddy' to transform the display — making the transformation accidental rather than intentional. Children performed significantly better, suggesting that the social context of the task (an adult deliberately changing the display then asking the question) misled pre-operational children into thinking the transformation was relevant. Samuel and Bryant (1983) replicated this using a modified procedure, confirming that Piaget underestimated the age of conservation acquisition. Baillargeon's research (B1548) similarly shows object permanence emerges much earlier than Piaget claimed.