11.1.2 Piaget's Stages of Intellectual Development

• The sensorimotor stage spans the ages from birth to around 2 years old and is marked by the child’s body schema and the physical exploration of their environment 
• Young children in this stage learn via a set of physical schemas e.g. sucking schema,trajectory schema etc. which are not reflexes; they are performed intentionally as the child derives pleasure from them (this explains why a baby might hurl their dish from their highchair and then laugh uproariously)
• 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 which involves hiding a toy under location A in front of the child for several times in a row and asking the child to retrieve the toy; the toy is then hidden under location B and if the child continues to look for the toy under location A they have failed the task (i.e. they have not acquired object permanence)
• Passing the ‘A-not-B’ task shows that the child understands that the toy still exists even though it cannot be seen and their initial reinforced (via several trials) movement to retrieve it from location A can be overridden by their new knowledge that the toy is in now in location B

The ‘A-not-B’ error - the child still thinks the toy has been hidden in its original position.

• The pre-operational stage is probably the most-researched of all four of Piaget’s stages as children show the most developmental milestones in this stage and they are more receptive to taking part in research compared to babies
• This stage spans the ages of 2-7 years old and is characterised by the development of increasingly sophisticated schemas, pretend play, anthropomorphism, an understanding of time and the ability to de-centre
• Key markers of this stage comprise:
  • Egocentrism –  lacking the ability to see the world from another’s perspective (passing an egocentrism task marks the end of this stage)
  • Conservation – lacking the ability to appreciate that objects or materials remain the same even when their appearance changes (passing a conservation task marks the end of this stage)
  • Class inclusion - lacking the ability to classify objects into two or more categories
• Piaget tested conservation using experimental methodology as follows:
  • The child is shown the material (liquid = conservation of volume; clay = conservation of mass or coins = conservation of number) in the same quantity side by side
  • The child is asked ‘Does this one have more, does this one have more or do they both have the same (volume/mass/number)?’
  • One of the items is transformed while the child is watching, by the researcher changing its appearance (eg pouring liquid into a different-sized container)
  • The child is asked for the second time, ‘Does this one have more, does this one have more or do they both have the same?’
  • If the child answers by saying that one of the materials now has more/less after the transformation they have failed the conservation task
  • If the child answers by saying that both materials are the same after the transformation they have passed the conservation task
  • Saying that one of the materials now has more/less fails the conservation task as it shows that the child's thinking lacks maturity as it focuses on appearance at the expense of logic
• The conservation task tests a key developmental milestone in children as to pass it the child must be able to perform a reverse operation i.e. by ‘conserving’ the idea that both materials are the same in terms of capacity so that they can go back (in their head) and see them as the same even when the transformed appearance of one of them makes them look as if they have different capacities
• Piaget tested egocentrism via a test known as the 3 Mountains Task which runs as follows:
  • A child is shown a 3-D model of a landscape which includes 3 mountains and other features e.g. an animal
  • The researcher sits opposite the child so that they also have a view (but - crucially - a different view to that of the child)
  • The child is asked to describe the view from their own perspective
  • The child is then asked to describe the view from the perspective of the researcher i.e. the person sitting opposite them
  • If the child describes the view as they themselves can see it i.e. from their own perspective rather than that of the person sitting opposite them then they have failed the 3 Mountains Task
• The 3 Mountains Task tests a key developmental milestone in children as to pass it the child must be able to de-centre i.e. to take on another person’s perspective or viewpoint
• Piaget tested class inclusion as follows:
  • A child is shown a picture or a model of, for example, a bunch of flowers
  • The bunch of flowers includes, for example, five daffodils and three poppies
  • The child is then asked, ‘Are there more daffodils or more flowers?’ 
  • If the child answers that there are more daffodils then they fail the class inclusion task
• The class inclusion 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’

• The concrete operational stage spans the ages 7-11 years and is marked by an understanding of the conservation of volume, mass and number, are able more easily to de-centre, and can classify and categorise objects more accurately
• Children in this stage can perform mental operations that require logic e.g. mathematics up to a certain point, but they may lack a systematic approach to problem-solving
• The formal operational stage spans the ages 11+ years and is marked by increasingly systematic and sophisticated mental operations, abstract thought, relativism and the ability to debate and manipulate ideas and principles

Research which investigates Piaget’s stages of intellectual development

• Samuel & Bryant (1984) found that by asking 4-8 year-old children only one question in total (after viewing the transformation of volume/mass/number) that children made fewer mistakes, even those aged 4 years old thus Piaget’s stages are not as inflexible as he suggested
• Piaget & Inhelder (1956) - The original 3 Mountains study as described above
• Hughes (1975) found that fewer children aged 3 to 5 years old fail a test of egocentrism if the procedure changes to include two policeman dolls that a boy doll has to hide from using four interlocking walls i.e. the children could understand that if the boy stood at point X then the policemen could not see him
• McGarrigle (1974) changed the wording of a standard Piagetian class inclusion task by asking pre-operational children if there were ‘more black cows or more sleeping cows?’ (the standard question was, ‘more black cows or more cows?’) - as the cows were placed lying down they appeared to be sleeping and this resulted in 48% of the children passing the test as opposed to 25% passing the standard Piagetian version

Evidence that children are less egocentric than Piaget thought.

Evaluation of Piaget’s stages of intellectual development

Strengths

• Piaget’s stage theory has great application to educational settings as it sets out the benchmarks for educators and health professionals to use to assess progress and flag any developmental delays that a child may be experiencing
• Piaget's stage theory changed the way that researchers think about children i.e. children are not simply smaller versions of adults: the way children think is fundamentally different from the way that adults think

Weaknesses

• Children do not develop synchronistically, achieving key milestones at exactly the same time, which means that the study lacks reliability as it is unlikely to show consistency across age groups and particularly across cultures
• Piaget’s original research has had to be modified over the years as the procedures can themselves constitute confounding variables e.g. how many children (or even adults)  are able to describe a mountainous landscape with ease if they have grown up in a non-mountainous region?

Link to Issues & Debates:

Piaget’s theory could be accused of being overly deterministic with its assumption that children pass through each developmental stage according to an age-determined timeline. Some children will move more quickly or slowly through the stages; some children may ‘peak’ in one stage but ‘plateau’ in another stage. The theory does not account for the key influence of social and cultural factors in cognitive development, both of which have a huge effect on cognitive development.