Piaget believed that the development of cognitive abilities occurs because of two factors, these are

1. Maturation of the Brain
   • As the brain grows and becomes more complex, this allows higher levels of thinking. However, this means that it is not possible for children to benefit from experience until their brain is sufficiently developed.
2. The child's interaction with the environment
   • Children are intrinsically motivated to explore and experiment with their environment. This led Piaget to describe children as little scientists.

Interaction with the environment challenges the child's view of the world when there are discrepancies between the child's current way of thinking and their experiences; the child is in a state of disequilibrium which leads to the development of schemas. Schemas are cognitive frameworks that enable the understanding of future experience, based on past experience; they are mental representations of the world.

Schemas develop through the process of equilibration, which is a biological drive to maintain equilibrium between how the world is represented in the mind and how it is perceived.

 

 

 

Another major aspect of Piaget's theory is that development progresses through 4 stages that are universal and invariant.

 

Stage	Approximate Age
Sensorimotor	0 – 2 Years
Preoperational	2 – 7 Years
Concrete Operations	7 – 11 Years
Formal Operations	11+

Piaget’s Stages of Cognitive Development

The Sensorimotor Stage 0-2 Years

In the sensorimotor stage, Learning is based on the senses (sensori-) and doing things (motor).

Object Permanence

The development of Object Permanence is one of the main characteristics of this stage. Object Permanence is the realisation that objects continue to exist even when they are not visible. This applies to people as well as inanimate objects. Piaget demonstrated that children in the sensorimotor stage lack object permanence in the following way:

An attractive toy, such as a colourful rattle, was waved in front of the infant, who then reached out to grasp the object. Instead of allowing the infant to take the object, Piaget hid it under a cloth. Piaget found that babies under the age of 8 months would immediately lose interest - as if the object had ceased to exist. Older infants would search for the object under the cloth.

Object Permanence develops in the following sequence:

1. No understanding of objects.
2. Looks where an object was last seen.
3. Realises that the visible portion of a partially hidden object is part of the whole object.
4. At about 8 months of age, the child is able to find a completely hidden object. However, if an object is hidden under cloth A and retrieved by the infant, then hidden under cloth B, in full view of the infant, they will search under cloth A.
5. The child will searches in location where the object was hidden (i.e., does not make the A not B error).
6. Will search for an object that is hidden when the infant is not looking. (18 months)
   
   

Object Permanence allows the infant to use symbolic thought. With object permanence, the infant can construct mental representations of objects. In the later sub-stages the infant is able to engage in goal directed behaviour and will solve simple problems. Language is an example of symbolic thought (words are symbols that are used to represent things).

The Preoperational Stage (Age: 2-7 Years)

This stage is characterised by an increase in the use of symbolic thought and the development of self-awareness. However, the child’s thinking is dominated by how things look, rather than logical principles or operations. Children in this stage are egocentric and are unable to conserve:

Egocentrism

This is the inability to see the world from another person’s viewpoint. According to Piaget, at this age the child does not understand that other people do not see exactly as they do. This was demonstrated in the “three mountains task"

Conservation

Preoperational children also have difficulty conserving. Conservation is the understanding that any quantity remains the same, despite any physical distortions. There are a number of different types of conservation:

• Conservation of Number
• Conservation of Liquid volume
• Conservation of Length
• Conservation of Amount of substance
  
  

E.g., Conservation of liquid volume

1. Water poured into two identical beakers.
2. Child agrees that they both contain the same amount.
3. Contents of one beaker then poured into a shorter, wider beaker
4. Child again asked if they contain the same amount.
   
   

Preoperational children claim that the taller beaker contains more water than the shorter, wider beaker.


If the liquid is poured back into the original glass, preoperational children will say that both glasses contain equal amounts of liquid. According to Piaget the child cannot perform this operation mentally. That is why this is called the preoperational stage; in this example, the child lacks the mental operation of “reversibility”. Other operations include compensation (the narrowness ‘cancels out’ the tallness). When the child progresses to the next stage (concrete operations) they can perform these operations mentally.

Piaget's Formal Operations Stage (11+ Years)

According to Piaget, at the age of about 11 or 12 children enter the formal operations stage, which allows them to manipulate ideas & concepts mentally and think about abstract principles.


It is called formal operations because they can follow the form of an argument without relating to its content, for example, algebra.


In algebra, the letters can represent any value as long as they obey the logical rules of the equation.

e.g., if x=y+2 and we know that y=2 then x=4. Similarly if we know that x=6 then we know that y=4.

Understanding that this logic applies to all values of x and y is difficult for people in the concrete operations stage. Algebra can be thought of as a type of formal logic.


People who have reached the formal operations stage are also able to think hypothetically. This means that they can think about situations that have not yet happened, are unlikey to happen or even impossible; for example, what it would be like if we had hands instead of feet and spoons instead of hands. People in this stage can deal with alternatives to reality, e.g., “what it would be like if there was a different political system?” This means that adolescents often question common assumptions like religion or capitalism (e.g., 'I've been told that there is a God, but that does not make sense because....' or 'wouldn't it be better if everybody cooperated and shared things according to each others' needs instead of having a selfish capitalist system?'). They are able to challenge these assumptions because they can now spot the inconsistencies (e.g., If there is a God who is all good and all powerful (as most religions contend) then how can bad things happen?)


Another major feature of the formal operations stage is the development of Inferential reasoning; in other words, they develop the ability to think in logical, systematic way. An example of this was Piaget and Inhelder's beaker problem, where a person is given the following task:


When the liquid from beaker g is added to a certain combination of the other beakers, the liquid will turn yellow. Find the combination.

Piaget believed that everybody reaches the formal operations stage by age 20, but that it may vary according to an individual's area of expertise. This means that some people will excel at formal reasoning, such as mathematics, while others will be more creative.

Evaluation of Piaget’s Theory

 

A major strength of Piaget’s theory is that he accounted for both biological factors and environmental factors in the development of intelligence.


These factors are:

1. Maturation of the brain
2. Interaction with the environment
   
   

However, unlike other theorists such as Vygotsky, Piaget ignored the role of social interaction. It seems highly likely that children’s learning is strongly influenced by teaching from adults.


It also seems that Piaget underestimated what children are capable of, this may be due to him using tasks that were overly difficult for children. For example, children in the Sensorimotor stage may not search for a hidden object because their motor skills are not developed, rather than because they lack object permanence. This has been supported by evidence from Bower & Wishart (1972). They found that the way that an object is made to disappear influences the child’s response.


Bower and Wishart made an object “disappear” by turning off the lights while infants were searching for the object. Using an infrared camera to observe babies in the dark, they found that infants continued to search for up to 1½ minutes. Other research by Bower (1974) found that 20 day old infants showed surprise when an object was not there after being hidden by a screen.


Similar results have been found in studies of egocentrism:


Gelman (1979) found that 4 year olds adjust their explanations so that blindfolded listeners can understand. He also noted that 4 year olds use simpler language when speaking to 2 year olds.

Marvin (1975) found that some 4 year olds choose presents for their mothers that are appropriate for their mothers, but not appropriate for them.


Margaret Donaldson (1984), a critic of Piaget’s, claims that the 3 mountains task was unrealistic and does not relate to a child’s everyday experience. She claims that Hughes’ study where children had to hide a doll from policemen was more realistic. In this study 90% of 3 ½ to 5 year olds were able to hide the doll successfully.


Piaget has also been criticised for his studies on conservation. According to Donaldson (1978), asking the same question twice “forces” children to give an answer that is against their better judgement. Rose & Blank (1974), for example, found that when the pre-transformation question is dropped, 6 year olds can succeed in a conservation of number task. Samuel & Bryant (1984) found similar results with conservation of liquid quantity and number.