Piaget’s theory of four stages of development has the dubious claim to fame of being one of the most criticised psychological theories ever.
Jean Piaget was a developmental psychologist whose four-stage theory, published in 1936, has proved extremely influential.
From the sensorimotor stage, through the pre-operational stage, the concrete operational stage and the formal operational stage, his theory attempts to describe how childhood development progresses.
However, Piaget’s experiments and theories about how children build up their knowledge of the world have faced endless challenges, many of them justified.
Let me give you a flavour of why Piaget’s research on stages of development has faced so much criticism and also why psychologists often regard him with such awe.
First I’ll describe one of the observations he made of his own three children, then why his conclusions are probably wrong and finally the central insight at the heart of his four-stage theory of cognitive development.
Piaget’s research on his daughter
One of Piaget’s many careful observations was made when one of his daughters, Jacqueline, then 7 months old, dropped a plastic duck on the quilt and it fell behind a fold so that she couldn’t see it.
Piaget noticed that despite the fact that Jacqueline could clearly see where the duck had dropped, and it was within her reach, she made no attempt to grab for it.
Fascinated by this, Piaget put the duck in her view again but, then, just as she was about to reach for it, he slowly and clearly hid it under the sheet.
Again, she acted as though the duck had simply disappeared, making no attempt to search for it under the sheet.
This seemed strange behaviour to Piaget as Jacqueline was clearly interested in the duck while she could see it, but seemed to forget about it the instant it disappeared from view – out of sight and, apparently, out of mind.
What Piaget deduced from these observations, along with many experiments, was that children do not initially understand the idea that objects continue to exist even when out of sight (this is known as object permanence).
This concept, he thought, children had to work out by themselves by interacting with and experiencing the world.
It wasn’t until around 9 or 10 months of age that Piaget noticed his children began to search for a hidden object.
Piaget’s four-stage theory of development
While many parents play games with their children like this, what set Piaget apart was that he used these observations along with many experiments to develop a theory of how children acquire knowledge, the stages of development theory for which he is rightly best-remembered.
This theory is a four-stage ladder up which Piaget thought children climbed as they gathered knowledge about the world (Piaget, 1936).
1. Sensorimotor stage (birth to 18-24 months)
At the first of Piaget’s stages of development, the sensorimotor stage, infants are aware only of their sensations, fascinated by all the strange new experiences their bodies are having.
They are like little scientists exploring the world by shouting at, listening to, banging and tasting everything.
2. Pre-operational stage (18-24 months to 7 years)
At the second of Piaget’s stages of development, the pre-operational stage, children can process images, words and concepts but they can’t do anything with them, they can’t yet operate on them.
It’s like they’ve acquired the tools of thought, but don’t yet know how to use them.
E.g. in maths they can’t understand that 2 x 3 is the same as 3 x 2.
3. Concrete operational stage (7 to 12 years)
At the third of Piaget’s stages of development, the concrete operational stage, children gain the ability to manipulate symbols and objects, but only if they are concrete – abstract operations are still a challenge.
4. Formal operational stage (12 and up)
At the fourth of Piaget’s stages of development, the formal operational stage, children are able to think in abstract terms about the world.
Now they can understand concepts such as the future, values and justice.
From around this age children start thinking like adults.
Criticism of Piaget stages of development theory
It’s for this grand stages of development theory that Piaget is much admired.
Unfortunately, like many an ambitious theory, over time evidence was uncovered that contradicted aspects of this neat time-line.
For example, Piaget’s conclusions about his daughter Jacqueline’s failure to reach for the duck were probably wrong.
Subsequent studies have revealed infants as young as 3.5 months appear to understand object permanence.
Psychologists nowadays might explain Jacqueline’s behaviour as a failure of memory or an inability to grasp something that is out of view.
Einstein though Piaget was a genius
Although findings such as these have chipped away at Piaget’s stages of development theory, his work has continued to attract interest and stimulate research.
From observations like hiding his daughter’s duck to his grand four-stage theory of development, Piaget’s central insight was that children think in a fundamentally different way from adults.
They don’t just have less knowledge, less experience or less processing power; the qualitative content of their thoughts is actually different.
Even though psychologists now question many of the details of Piaget’s observations and theories, this central insight remains intact.
And it’s this central insight that Albert Einstein once described as “so simple that only a genius could have thought of it”.
→ This article is part of a series on 10 crucial developmental psychology studies:
- When infant memory develops
- How self-concept emerges in infants
- How children learn new concepts
- The importance of attachment styles
- When infants learn to imitate others
- Theory of mind reveals the social world
- Understanding object permanence
- How infants learn their first word
- The six types of play
- Piaget’s stages of development theory
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