Human Development: Piaget's Theory (DP IB Psychology): Revision Note

Piaget's theory of cognitive development

• Piaget’s theory of cognitive development (1920s-1980s) proposed that children’s thinking is qualitatively different from that of adults

• He argued that cognitive development is maturational, meaning progress is tied to age and follows a biologically driven timetable

• Piaget believed that children actively explore their environment through discovery learning, behaving like ‘little scientists’

• As they interact with their surroundings, children construct schemas — mental frameworks that help them organise and interpret information

• These schemas develop through two processes:

  • Assimilation: fitting new experiences into existing schemas

  • Accommodation: altering schemas when new experiences don’t fit

• Piaget described this overall framework as genetic epistemology, meaning knowledge develops from innate drives to explore and learn, unfolding according to age-related stages

Piaget's stage theory

The sensorimotor stage (0-2 years)

• This stage is marked by the child’s body schema and the physical exploration of their environment 

• A key marker of this stage of cognitive development is when a baby acquires object permanence, usually around the age of 8 months

• Object permanence can be tested using the ‘A-not-B’ task: a toy is repeatedly hidden under location A, then under location B. If the child continues to search at A, they have not yet acquired object permanence

The pre-operational stage (2-7 years)

• The pre-operational stage is the most widely researched stage, as children show rapid developmental milestones and are receptive to experiments

• This stage is characterised by increasingly sophisticated schemas, pretend play, anthropomorphism, early concepts of time and the beginnings of decentration

• Key markers of this stage include:

  • egocentrism – inability to see from another’s perspective (passing an egocentrism task marks the end of this stage)

  • conservation – failure to understand that quantity remains the same despite changes in appearance (passing a conservation task signals transition to the next stage)

  • class inclusion – inability to classify an object as belonging to multiple categories at once

The concrete operational stage (7-11 years)

• Children begin to understand conservation of volume, mass, and number

• They can de-centre and classify/categorise objects more accurately

• They can perform logical mental operations (e.g., mental maths) but often lack systematic problem-solving strategies

The formal operational stage (11 years +)

• This stage is marked by the ability for abstract reasoning, systematic and scientific thinking, relativism, and debating complex ideas

Research support for human development: Piaget’s theory

Conservation: Piaget

• Present equal quantities

  • Show the child two equal amounts of material side by side (e.g., liquid in identical glasses, equal clay balls, or equal rows of coins)

• Initial question

  • Ask, "Does this one have more, does that one have more, or are they the same?"

• Transform one item

  • While the child watches, alter the appearance of one material (e.g., pour liquid into a taller container, flatten one clay ball, spread out one row of coins)

• Repeat the question

  • Ask the same question again: “Does this one have more, does that one have more, or are they the same?”

• Evaluate the response

  • If the child says one now has more/less: Fail – they focus on appearance, not logic

  • If the child says they’re still the same: Pass – they understand conservation

• The conservation task tests a key developmental milestone in children, as to pass it, the child must be able to perform a reverse operation

  • This means that they can ‘conserve’ the idea that both materials are the same in terms of volume/number

Egocentrism: Piaget & Inhelder (1956) - 3 Mountains task

• Present the model

  • Show the child a 3D model landscape with three mountains and features like animals or trees

• Introduce the doll

  • Place a doll on the opposite side of the model, facing the landscape from a different viewpoint than the child

• Ask the perspective question

  • Ask the child, “What does the doll see?”

  • The child selects a picture from several images showing the model from different angles

• Observe the response

  • Young children (around 4 years old) typically choose the image that matches their own view – showing egocentrism

  • By age 7–8, children more consistently select the doll’s viewpoint – showing reduced egocentrism and improved perspective-taking

• The 3 Mountains Task tests a key developmental milestone because to pass it, the child must be able to decentre and recognise others' viewpoints

Class inclusion: Piaget

• Present the Set

  • Show the child a picture or model of a set of items, e.g., a bunch of flowers

• Identify Subclasses

  • The set includes two subgroups — for example, five daffodils and three poppies

• Ask the Inclusion Question

  • Ask the child, “Are there more daffodils or more flowers?”

• Evaluate the Response

  • If the child answers “more daffodils”, they fail the class inclusion task, showing they do not yet understand that “flowers” includes both daffodils and poppies

  • If the child answers “more flowers”, they pass, demonstrating an understanding of hierarchical categorisation

• The task tests a key developmental milestone in children, as to pass it, the child must be able to understand that ‘daffodils’ are a subcategory of the overarching category of ‘flowers’

Evaluation of Piaget’s theory

Strengths

• Piaget’s theory can be easily tested using experimental methodology, which means that it is reliable

• Piaget's theory was groundbreaking; Piaget’s work shifted psychology toward recognising children’s cognitive development, sparking decades of valuable research

Limitations

• Piaget’s theory does not consider the role of language in a child's cognitive development

  • This means that it is an incomplete explanation of the different aspects of developing cognition

• Piaget’s theory was not initially supported by empirical evidence; his ideas were formed using a small, biased sample of Swiss children and anecdotal observation rather than robust empirical methods

Link to concepts

Bias

• Piaget’s theory and the tests he devised show culture bias

  • The 3 Mountains Task is based on Swiss landscapes — unfamiliar to children from non-mountainous areas

  • Conservation tasks reflect Western/individualistic ideas of volume, mass, and number, excluding collectivist cultural understandings

Responsibility

• Research with children requires strict adherence to ethical guidelines:

  • Informed consent from parents/guardians

  • Protection from harm and ensuring tasks are not distressing

  • Extra care in wording instructions, since children may not understand in the same way as adults