Schema, assimilation, accommodation and equilibration

For Piaget, children are active scientists constructing their own understanding of the world; they are not passively taught it.

• Schema — mental frameworks of knowledge. Babies are born with a small number of innate schema (sucking, grasping) and construct many more, including the crucial 'me-schema'.
• Assimilation — incorporating new information into an existing schema, which is not radically changed. A child who knows 'dog' and sees a new breed of dog assimilates it.
• Accommodation — a dramatically new experience requires the schema to be changed, or a whole new schema formed. The child who calls a horse a 'dog' and is corrected must form a new schema.
• Equilibration — the driving force. Encountering something we cannot explain produces an unpleasant state of disequilibrium; to escape it, we explore and learn until balance is restored. Learning is therefore motivated by cognitive conflict.

Evaluation: Piaget's account of learning through discovery has been enormously influential in education: the modern primary classroom, with its activity-based, discovery learning, is Piaget's legacy. But his emphasis on the individual child constructing knowledge alone under-plays the role of other people — the criticism Vygotsky makes. There is also good evidence that Piaget's methods under-estimated children: his tasks were confusing and used unfamiliar language, and simpler versions show children can do far more than he thought.

Piaget's four stages of intellectual development

• Sensorimotor (0–2) — the infant learns by physical interaction, coordinating sensory input with motor action. The key achievement is object permanence, at about 8 months: the understanding that an object continues to exist when it is out of sight. Piaget's evidence was that before 8 months, an infant will simply stop looking when a toy is covered by a blanket, as though it had ceased to exist.
• Pre-operational (2–7) — the child is mobile and using language, but their reasoning has three characteristic limitations:
  • Conservation — the failure to grasp that quantity remains constant when appearance changes. Shown two identical rows of counters, then one row spread out, a pre-operational child says the longer row has more counters. The same happens with liquid poured into a taller, thinner glass.
  • Egocentrism — the inability to see the world from another's point of view. Piaget and Inhelder's three mountains task: shown a model of three mountains and asked to select the picture showing what a doll placed elsewhere could see, pre-operational children chose the picture of their own view.
  • Class inclusion — the failure to grasp that classes have sub-classes. Shown a picture of five dogs and two cats and asked whether there are more dogs or more animals, children under 7 typically say 'more dogs'.
• Concrete operational (7–11) — the child now has mastered conservation, egocentrism and class inclusion, but can apply their reasoning only to physical, concrete objects that are in front of them. Abstract or hypothetical reasoning remains poor.
• Formal operational (11+) — the capacity for abstract and hypothetical reasoning, and for systematic scientific testing. Piaget tested it with syllogisms ('all yellow cats have two heads; I have a yellow cat called Charlie; how many heads does Charlie have?') — formal operational thinkers can reason from the premises even though the content is absurd.

Evaluation: the tasks may have under-estimated children badly. Hughes (1975) used a 'policeman doll' task, in which a child had to hide a boy doll from one or two policemen — a scenario that made 'human sense' to a child. 90% of children aged 3½ to 5 could position the doll so that neither policeman could see him, a task requiring exactly the perspective-taking Piaget said they lacked. McGarrigle and Donaldson (1974) found that when a 'naughty teddy' knocked the counters out of line 'accidentally', far more children correctly conserved — implying the original task failed because children thought the deliberate change by the experimenter must mean something. So the stages, and especially the ages, are probably wrong — though the broad sequence is well supported.

Which stage, which limitation?

Vygotsky — the social construction of thought

Vygotsky agreed that children's reasoning develops in a sequence, but argued cognitive development is fundamentally a social process: knowledge is first intermental (between the child and a more expert other) and only then becomes intramental (within the child). Culture, and especially language, is therefore the vehicle of cognitive development — which explains why children in different cultures acquire different reasoning tools.

• The zone of proximal development (ZPD) — the gap between what a child can do alone and what they can achieve with expert help. Vygotsky argued that the right teaching, aimed at the ZPD, allows the child to cross the gap and reach their potential.
• Scaffolding — the help given to cross the ZPD. Wood et al. (1976) identified levels of help, from the most to the least intrusive: demonstration → preparation for the child → indication of materials → specific verbal instruction → general prompts. Effective scaffolding is progressively withdrawn as competence grows.

Evaluation: the ZPD has clear research support: Roazzi and Bryant (1998) gave 4–5 year-olds the task of estimating sweets in a jar. Working alone, most failed. Working with an older child who offered prompts, most gave the correct answer — showing that expert scaffolding really does allow a child to work at a higher level. Vygotsky's ideas have transformed education, providing the rationale for peer tutoring and group work in classrooms. But Vygotsky may over-play the social and under-play individual differences — some children learn perfectly well through independent discovery, and Howe et al. found that children working in groups did not all end up at the same level of understanding, so the child's own contribution clearly matters. The two theories are best seen as complementary, not rivals.

Vygotsky's key concept

Baillargeon — violation of expectation

Baillargeon argued Piaget's object permanence tasks were unfair: an infant who does not reach for a hidden object may simply be uninterested or unable to coordinate the search. She developed the violation of expectation (VOE) method: infants should look for longer at an event that violates their expectations.

Baillargeon and Graber (1987) showed 24 infants aged 5–6 months a tall and a short rabbit passing behind a screen with a window in it. In the possible event, the short rabbit passed behind the screen and did not appear in the window (it was too short). In the impossible event, the tall rabbit passed behind and — impossibly — did not appear in the window either. Infants looked at the impossible event for an average of about 33 seconds, compared with about 26 seconds for the possible event. The infants were therefore surprised — which means they had expected the tall rabbit to appear, so they must have understood that it continued to exist behind the screen.

Conclusion. Baillargeon proposed that infants have an innate physical reasoning system (PRS) — a primitive, hard-wired awareness of the physical properties of the world, present much earlier than Piaget claimed. Experience refines it, but the basic understanding is innate.

Evaluation: the VOE method is a huge methodological advance, because it removes the confound of an infant's poor motor coordination, and the studies are tightly controlled laboratory experiments with clear operationalisation of the DV (looking time). The interpretation, however, is disputed. Looking longer at an impossible event shows the infant finds it surprising, but it does not prove the infant has an understanding of object permanence in the rich sense Piaget meant — Bremner argues we cannot know what the infant is thinking, only what it is looking at. The design also requires the assumption that all infants share the same expectations, which may not hold.

Selman's levels of perspective-taking

Selman (1971) took a cognitive approach to social development: what changes with age is the child's ability to take another's perspective. He gave 30 boys and 30 girls (aged 4–6, 7–9 and 10–12) social dilemmas to solve, the best known being Holly, who has promised her father she will not climb trees but finds her friend's kitten stuck up one.

• Level 0 — Egocentric (3–6). The child cannot distinguish their own perspective from another's, and assumes everyone feels as they do.
• Level 1 — Social-informational (6–8). The child understands that a different perspective exists, but assumes it is because the other person has different information.
• Level 2 — Self-reflective (8–10). The child can put themselves in another's shoes and appreciate their point of view, but can only consider one perspective at a time.
• Level 3 — Mutual (10–12). The child can step outside the situation and view both perspectives simultaneously, as a third party.
• Level 4 — Social and conventional system (12+). The young person understands that perspectives are shaped by wider social conventions, and that mutual understanding may require reference to shared social norms.

Evaluation: Selman's levels have good research support: Gurucharri and Selman (1982) followed children longitudinally for two years and found perspective-taking ability did indeed improve with age in the predicted sequence — evidence that the levels are a genuine developmental progression. But Selman's account is purely cognitive: social development is far more than perspective-taking, and the theory neglects the influence of emotion, attachment and the child's family environment. The dilemmas themselves may also lack ecological validity — reasoning about Holly is not the same as behaving well in a real playground conflict.

Theory of mind and the mirror neuron system

Theory of mind (ToM) — our ability to 'mind-read', i.e. to attribute mental states (beliefs, desires, intentions) to ourselves and to others, and to understand that others' beliefs may be false.

• False belief tasks. Wimmer and Perner (1983) told 3- and 4-year-olds a story in which Maxi puts his chocolate in a blue cupboard and leaves; his mother moves it to a green one. Asked where Maxi will look, most 3-year-olds said the green cupboard (their own knowledge), while most 4-year-olds correctly said the blue one — a ToM appears at about 4.
• The Sally-Anne study. Baron-Cohen et al. (1985) tested 20 children with autism, 14 with Down's syndrome and 27 without a diagnosis. Sally places a marble in her basket and leaves; Anne moves it to a box. Asked where Sally will look, 85% of the children in the two control groups answered correctly, but only 20% of the children with autism did — despite the Down's syndrome group having lower mental age. This suggested ToM deficit, not general intellectual impairment, might explain the social difficulties of autism.
• The Eyes Task. Baron-Cohen et al. (1997) developed a test of adult ToM in which participants must read complex emotions from photographs of the eye region alone. Adults with autism or Asperger's syndrome performed less well than controls.

The mirror neuron system. Rizzolatti et al. discovered — by accident, while recording from a monkey's motor cortex — that the same neurons fired both when the monkey performed an action and when it observed a researcher performing that action. Gallese and Goldman proposed that mirror neurons are the neural basis of simulating another's action and thus inferring their intention — the biological substrate of theory of mind and of empathy. Ramachandran has argued that mirror neurons are so central to human social life that they drove the evolution of culture, and proposed the 'broken mirror' theory of autism: a dysfunctional mirror neuron system explains the social and communicative difficulties associated with autism.

Evaluation: ToM research is powerful, but false-belief tasks may simply measure working memory and executive function — the child must hold two conflicting representations in mind — rather than ToM as such. It is also unlikely that a single cognitive deficit explains a condition as varied as autism, and the ToM account cannot explain non-social features such as repetitive behaviours. The mirror neuron evidence is largely correlational and indirect in humans: recording directly from single neurons is invasive, so most human evidence comes from brain imaging, and Hickok has argued that the case for mirror neurons underpinning intention-understanding is over-stated. The 'broken mirror' theory of autism is also inconsistent with evidence that people with autism can imitate perfectly well when instructed to.

Read the Sally-Anne data

Assimilation or accommodation?

Class inclusion

What drives learning?

Vygotsky vs Piaget

What does looking time show?

Selman's levels

Whose theory?

Tap a concept, then the theorist it belongs to.

Study and finding

Tap an item on the left, then its partner on the right.

The big ideas to know

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