Some years ago, Jean Piaget’s (1896 - 1980) theory of cognitive development during childhood was regarded as the major paradigm in which to understand the complex procedure of mental progression through different levels of thinking and understanding. One of the most important contributions that Piaget made, was to establish the fact that the cognitive processes of young children are not simply immature versions of that of an adult, but that they have their very own rules. As will become apparent in this essay Piaget’s theory and in fact his findings have been widely challenged. Never the less, Piaget’s ideas still maintain a vital influence in both general psychology and contemporary education.

Piaget contended that cognitive development can be divided into four stages. This essay will examine each stage individually and then evaluate Piaget’s theories by exploring some of the major criticisms and supporting views. It is not possible, within the constraints of this essay to describe Piaget’s (or others) experiments in any great detail. However, a brief summary of methodologies and findings will be included.

Each stage is characterised by an overall structure and a sequence of development which occurs within this structure. According to Piagetian theory, these structures consist of "schemas", which are essentially, ways of organising experience. According to Piaget, schemas are the primary component of intelligent behaviour. These schemas adapt through a continuous process of "assimilation" and "accommodation," in an endeavour to attain "equilibrium" which is essentially balance. Assimilation is the process of adapting new experiences to fit into existing schemas. Accommodation is the process of changing existing schemas to fit new experiences.

The first of Piaget’s stages of cognitive development is the "sensorimotor stage". This stage occurs around 0-2 years. It is essentially a stage of practical discovery, which occurs by interaction with the environment through the senses and by using motor skills. A baby accommodates and assimilates information which it encounters into schemas.

Piaget contends that a baby is born with no sense of "object permanence". This is the understanding that objects continue to exist in their own right, when they are not being directly manipulated or immediately perceived. Piaget conducted an experiment to demonstrate the failure of object permanence on his daughter Jacqueline. This involved her trying to locate a rattle under a bed cover. He concluded from his observations of infants that it is during the first 2 years of a baby’s life (during the sensorimotor stage) that it acquires object permanence. (Piaget 1963).

The other major progression in the sensorimotor stage is the development of what Gleitman calls "the beginnings of representational thought." (Gleitman 1995). This term refers to the acquisition of language, make believe play and deferred imitation. Deferred imitation is the imitation of an action which has occurred sometime in the past.

The second of Piaget’s stages is the "pre-operational stage". This stage lasts from around 2 - 7 years. Piaget contended that at this time a child fails to "conserve". This is basically the understanding that things remain constant in terms of number, quantity and volume regardless of changes in appearance. In experiments to test number conservation, Piaget showed the child two sets of checkers which had exactly the same number of checkers in each set. He then re-arranged one of the sets, keeping the same amount of checkers in it, so that it was only different in appearance. In Piaget’s findings the children in this stage of development believed that the sets were in fact of different quantity. Piaget argued that this occurred because the child is unable to conserve previous information. (Piaget 1952).

Within the pre-operational stage, Piaget identified a characteristic that he referred to as "egocentrism." This is the child’s inability to see the world from another’s perspective. They are quite literally self-centred. Piaget observed this phenomenon in his "Three mountains scene" experiment (Piaget & Inhelder, 1956). In this experiment the child was sat on one side of a model of three mountains, with a teddy sat at the opposite side. The child was asked to choose a picture which showed the scene that the teddy was able to see. Piaget discovered that until the age of seven, a child is unable to perceive a different viewpoint, from its own and is therefore said to be egocentric. Piaget saw many of the problems of the pre-operational stage child resulting from this inability to "de-centre".

The next stage is the "concrete operations" stage which lasts from about age 7 - 11 years. In this stage, children can perform operations requiring logic such as conservation. But this ability only holds for what he called concrete situations. That is, the child is only able to perform mental actions on actual objects and not in abstract terms. In the concrete operational stage, the child is no longer egocentric and now has the ability to de-centre.

Beyond 11 years the child is said to enter the final stage in cognitive development which is the "formal operations" stage. In this period, the child is able to think and reason scientifically. The child is also able to imagine and deliberate that which has never actually been encountered.

Piaget’s theories and findings have been widely challenged. Psychologists such as Meadows (1988) have suggested that Piaget underestimated the cognitive abilities of children. Meadows believes that Piaget ignored individual differences in his studies. It has also been argued that Piaget ignored both emotional and social influences on cognitive development.

One aspect of Piaget’s work which has frequently come under criticism is his methodology. In his experiments he used basic question and answer techniques. But his questions were not standardised and tailored very much to the individual. Additionally, he used no statistical analysis of his results. This makes them very difficult to translate and to make comparisons between children.

Ginsberg (1981) and Dansen argue that Piaget’s methods of study children excellent for examining "the subtleties of the child’s cognitive structure." However, it has been suggested that the instructions given to the children in Piaget’s experiments were perhaps difficult for children to understand, and easily misunderstood. Piaget asked the children the same questions more than once, and it has been argued that this could quite possibly cause confusion as it may have led the children to believe that the original answer that they gave was incorrect. Rose and Blank (1974) and Samuel and Bryant (1984) recreated Piaget’s conservation experiments. They asked only one question and both experiments produced very different results to Piaget’s in that the children made very few errors.

In his original theory, Piaget saw cognitive development as happening in discrete stages. This has been widely disputed in contemporary psychology. Even Piaget himself, in 1970, said that cognitive development was more like a "spiral" process of changes than one of discrete stages. Meadows found inconsistencies in the performance of children within the stages of development. Her findings showed that cognitive progression does not necessarily occur at exactly the ages Piaget predicted. Some cognitive processes may in fact develop at different speeds. The stages are now seen by many psychologists as overlapping and therefore more continuous than discrete in nature.

According to Piaget, it should not be possible to accelerate the cognitive development through the various stages. Meadows (1988) argued to the contrary that training does in fact produce improvements in performance, which can be quite notable and long lasting. For example, pre-school age children have been successfully taught to perform concrete operational assignments three to four years ahead of time. Their competence in these tasks was comparable to untrained eight-year-olds. However, other experiments to accelerate the learning process have produced more ambiguous results. Price-Williams, Gordon & Ramierez (1969) conducted an experiment in a Mexican village where the native children made pottery to earn a living. When these children were tested for conservation of mass their answers were found to be significantly more advanced than in Western children. However, these mental processes were specifically limited to conserving mass in clay and to very little else.

It may be so that the discrete nature of Piaget’s stage theory has been challenged, but there is evidence to support Piaget’s idea of discrete stages. In fact, it is widely accepted that some sequence does exist. It is true that eight-year-old children are definitely more advanced than pre-school age children are. It is also a fact that many modern day developmental psychologists use very similar age boundaries to distinguish the developing periods in a child’s life as those which were originally put forward by Piaget.

Turning now to the more specific criticisms of Piaget’s theory, according to Piagetian theory, failure of object permanence is characteristic of the sensorimotor stage, which can be observed until eighteen months. Many experiments have been conducted which dispute this finding. Baillargeon (1987) conducted one such experiment in which four and a half-month-old babies were shown a model of a stage upon which was a box. In front of the box was a screen which was initially laid flat so that the box could be seen clearly. The screen was lifted upwards to hide the box while the experimenter secretly removed the box. The infant showed expressions of surprise when the screen moved backwards passing through the space where the box was supposed to be.

Criticisms have also been made of Piaget’s ideas about egocentrism. It has been argued that Piaget’s egocentrism experiments, like the three mountain scene, confused the child as it was not clear what was being asked. Donaldson (1978) refers to experiments as being much easier to understand as they were more readily related to the world of the child. In Hughes’ experiment a toy doll was hidden out of the view of a toy policeman. Ninety percent of three and a half to five year olds could see from the toy policeman’s point of view. Even sixty percent of three-year-olds answered correctly. It has not however, generally been disputed that egocentrism exists at all, but simply at what age it occurs.

Further criticisms have been made regarding Piaget’s theory of conservation. It has been argued that it may well be difficult to interpret exactly what a child is referring to when it answers that something is "more" than something else is. Who is to say what the child’s interpretation of more might actually be?

Finally, evidence has been put forward to suggest that in fact only a small minority of adults tested in Western samples have actually acquired formal operations at all. As a result of cross-cultural studies conducted by Dansen (1994) the ability to think about abstract concepts is said not to exist at all in some areas of the world.

There are many other experiments which invalidate Piaget’s claims, but unfortunately it is not practical to cite them all in the confines of this essay. Piaget’s impact upon child psychology has been tremendous. Largely as a result of his work, a vast body of research has arisen to test his theories and confirm or refute his claims. For many years teachers have revised their approach in the classroom and applied Piagetian principles. For example, Piaget saw children as being actively involved in their own learning and he proposed that letting children discover things for themselves was by far the best way to learn. In fact, many current teaching strategies encourage this so-called student centred learning. Teachers also, often discourage signs of egocentrism by encouraging children to interact with each other and learn from one another’s differing perspectives. Another enduring legacy of Piaget’s work is the fact that many modern day psychologists do in fact use very similar age boundaries to describe periods of cognitive develop as those described in Piaget’s stage theory.

Despite the numerous objections to Piaget’s theory of cognitive development, he was in fact the first psychologist to even look at how children see the world and as a consequence initiated a vast amount of further study into the area. In those terms he has made a substantial contribution to our understanding and appreciation of this complex subject area. As we have seen, much of his theory has been directly applied and accepted in modern education. Many of the criticisms of Piaget surround his underestimation of childhood abilities and also the age at which the cognitive developments are said to take place. It is not however, disputed that the changes themselves do in fact occur, so in that respect, Piaget’s work has been and still is greatly significant.

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