a comprehensive theory about the nature and development of human intelligence, first developed

by Swiss developmental psychologist Jean Piaget . It is primarily known as a developmental

stage theory but, in fact, it deals with the nature of knowledge itself and how humans

come gradually to acquire, construct, and use it. To Piaget, cognitive development was

a progressive reorganization of mental processes as a result of biological maturation and environmental

experience. Accordingly, children construct an understanding of the world around them,

then experience discrepancies between what they already know and what they discover in

their environment. Moreover, Piaget claimed the idea that cognitive development is at

the center of human organism, and language is contingent on cognitive development. Below

is a short description of Piaget's views about the nature of intelligence, followed by a

description of the stages through which it develops until maturity.

Nature of intelligence: operative and figurative Piaget noted reality in the sense of as a

dynamic system of continuous change and, as such, is defined in reference to the two conditions

that define dynamic systems. Specifically, he argued that reality involves transformations

and states. Transformations refer to all manners of changes that a thing or person can undergo.

States refer to the conditions or the appearances in which things or persons can be found between

transformations. For example, there might be changes in shape or form (for instance,

liquids are reshaped as they are transferred from one vessel to another, humans change

in their characteristics as they grow older), in size (for example, a series of coins on

a table might be placed close to each other or far apart), or in placement or location

in space and time (e.g., various objects or persons might be found at one place at one

time and at a different place at another time). Thus, Piaget argued, if human intelligence

is to be adaptive, it must have functions to represent both the transformational and

the static aspects of reality. He proposed that operative intelligence is responsible

for the representation and manipulation of the dynamic or transformational aspects of

reality, and that figurative intelligence is responsible for the representation of the

static aspects of reality. Operative intelligence is the active aspect

of intelligence. It involves all actions, overt or covert, undertaken in order to follow,

recover, or anticipate the transformations of the objects or persons of interest. Figurative

intelligence is the more or less static aspect of intelligence, involving all means of representation

used to retain in mind the states (i.e., successive forms, shapes, or locations) that intervene

between transformations. That is, it involves perception, imitation, mental imagery, drawing,

and language. Therefore, the figurative aspects of intelligence derive their meaning from

the operative aspects of intelligence, because states cannot exist independently of the transformations

that interconnect them. Piaget stated that the figurative or the representational aspects

of intelligence are subservient to its operative and dynamic aspects, and therefore, that understanding

essentially derives from the operative aspect of intelligence.

At any time, operative intelligence frames how the world is understood and it changes

if understanding is not successful. Piaget stated that this process of understanding

and change involves two basic functions: assimilation and accommodation.

Assimilation and accommodation Through his study of the field of education,

Piaget focused on two processes, which he named assimilation and accommodation. Assimilation

describes how humans perceive and adapt to new information. It is the process of fitting

new information into pre-existing cognitive schemas. Assimilation occurs when humans are

faced with new or unfamiliar information and refer to previously learned information in

order to make sense of it. Unlike it, accommodation is the process of taking new information in

one's environment and altering pre-existing schemas in order to fit in the new information.

Through a series of stages, Piaget explains the ways in which characteristics are constructed

that lead to specific types of thinking. This chart is called cognitive development. To

Piaget, assimilation is integrating external elements into structures of lives or environments,

or those we could have through experience. It is through assimilation that accommodation

is derived. Accommodation is imperative because it is how people will continue to interpret

new concepts, schemas, frameworks, and more. Assimilation is different from accommodation

by how it relates to the inner organism due to the environment. Piaget believes that the

human brain has been programmed through evolution to bring equilibrium, which is what Piaget

believes ultimately influences structures by the internal and external processes through

assimilation and accommodation. Piaget's understanding is that these two functions

cannot exist without the other. To assimilate an object into an existing mental schema,

one first needs to take into account or accommodate to the particularities of this object to a

certain extent. For instance, to recognize (assimilate) an apple as an apple, one must

first focus (accommodate) on the contour of this object. To do this, one needs to roughly

recognize the size of the object. Development increases the balance, or equilibration, between

these two functions. When in balance with each other, assimilation and accommodation

generate mental schemas of the operative intelligence. When one function dominates over the other,

they generate representations which belong to figurative intelligence.

Sensorimotor stage The sensorimotor stage is the first of the

four stages in cognitive development which "extends from birth to the acquisition of

language". In this stage, infants progressively construct knowledge and understanding of the

world by coordinating experiences (such as vision and hearing) with physical interactions

with objects (such as grasping, sucking, and stepping). Infants gain knowledge of the world

from these physical actions they perform within it. They progress from reflexive, instinctual

action at birth to the beginning of symbolic thought toward the end of the stage.

The child learns that he/she is separate from the environment and that aspects of the environment

continue to exist, even though they may be outside the reach of the child's senses. In

this stage, according to Piaget, the development of object permanence is one of the most important

accomplishments. Object permanence is a child’s understanding that objects continue to exist

even though they cannot be seen or heard. Piaget divided the sensorimotor stage into

six sub-stages". By the end of the sensorimotor period, the

child sees objects as both separate from the self, and permanent.

Pre-operational stage Piaget's second stage, the pre-operational

stage, starts when the child begins to learn to speak at age two and lasts up until the

age of seven. During the Pre-operational Stage of cognitive development, Piaget noted that

children do not yet understand concrete logic and cannot mentally manipulate information.

Children’s increase in playing and pretending takes place in this stage. However, the child

still has trouble seeing things from different points of view. The children's play is mainly

categorized by symbolic play and manipulating symbols. Such play is demonstrated by the

idea of checkers being snacks, pieces of paper being plates, and a box being a table. Their

observations of symbols exemplifies the idea of play with the absence of the actual objects

involved. By observing sequences of play, Piaget was able to demonstrate that, towards

the end of the second year, a qualitatively new kind of psychological functioning occurs,

known as the Pre-operational Stage. The pre-operational stage is sparse and logically

inadequate in regard to mental operations. The child is able to form stable concepts

as well as magical beliefs. The child, however, is still not able to perform operations, which

are tasks that the child can do mentally, rather than physically. Thinking in this stage

is still egocentric, meaning the child has difficulty seeing the viewpoint of others.

The Pre-operational Stage is split into two substages: the symbolic function substage,

and the intuitive thought substage. The symbolic function substage is when children are able

to understand, represent, remember, and picture objects in their mind without having the object

in front of them. The intuitive thought substage is when children tend to propose the questions

of "why?" and "how come?" This stage is when children want the knowledge of knowing everything.

Symbolic function substage At about two to four years of age, children

cannot yet manipulate and transform information in a logical way. However, they now can think

in images and symbols. Other examples of mental abilities are language and pretend play. Symbolic

play is when children develop imaginary friends or role-play with friends. Children’s play

becomes more social and they assign roles to each other. Some examples of symbolic play

include playing house, or having a tea party. Interestingly, the type of symbolic play in

which children engage is connected with their level of creativity and ability to connect

with others. Additionally, the quality of their symbolic play can have consequences

on their later development. For example, young children whose symbolic play is of a violent

nature tend to exhibit less prosocial behavior and are more likely to display antisocial

tendencies in later years. In this stage, there are still limitations,

such as egocentrism and precausal thinking. Egocentrism occurs when a child is unable

to distinguish between their own perspective and that of another person. Children tend

to stick to their own viewpoint, rather than consider the view of others. Indeed, they

are not even aware that such a concept as "different viewpoints" exists. Egocentrism

can be seen in an experiment performed by Piaget and Swiss developmental psychologist

Bärbel Inhelder, known as the three-mountain problem. In this experiment, three views of

a mountain are shown to the child, who is asked what a traveling doll would see at the

various angles. The child will consistently describe what they can see from the position

from which they are seated, regardless of from what angle they are asked to take the

doll's perspective. Egocentrism would also cause a child to believe, "I like Sesame Street,

so Daddy must like Sesame Street, too". Similar to preoperational children's egocentric

thinking is their structuring of a cause and effect relationships. Piaget coined the term

"precausal thinking" to describe the way in which preoperational children use their own

existing ideas or views, like in egocentrism, to explain cause-and-effect relationships.

Three main concepts of causality as displayed by children in the preoperational stage include:

animism, artificialism and transductive reasoning. Animism is the belief that inanimate objects

are capable of actions and have lifelike qualities. An example could be a child believing that

the sidewalk was mad and made them fall down, or that the stars twinkle in the sky because

they are happy. Artificialism refers to the belief that environmental characteristics

can be attributed to human actions or interventions. For example, a child might say that it is

windy outside because someone is blowing very hard, or the clouds are white because someone

painted them that color. Finally, precausal thinking is categorized by transductive reasoning.

Transductive reasoning is when a child fails to understand the true relationships between

cause and effect. Unlike deductive or inductive reasoning (general to specific, or specific

to general), transductive reasoning refers to when a child reasons from specific to specific,

drawing a relationship between two separate events that are otherwise unrelated. For example,

if a child hears the dog bark and then a balloon popped, the child would conclude that because

the dog barked, the balloon popped. Intuitive thought substage

At between about the ages of 4 and 7, children tend to become very curious and ask many questions,

beginning the use of primitive reasoning. There is an emergence in the interest of reasoning

and wanting to know why things are the way they are. Piaget called it the "intuitive

substage" because children realize they have a vast amount of knowledge, but they are unaware

of how they acquired it. Centration, conservation, irreversibility, class inclusion, and transitive

inference are all characteristics of preoperative thought.

Centration is the act of focusing all attention on one characteristic or dimension of a situation,

whilst disregarding all others. Conservation is the awareness that altering a substance's

appearance does not change its basic properties. Children at this stage are unaware of conservation

and exhibit centration. Both centration and conservation can be more easily understood

once familiarized with Piaget's most famous experimental task.

In this task, a child is presented with two identical beakers containing the same amount

of liquid. The child usually notes that the beakers do contain the same amount of liquid.

When one of the beakers is poured into a taller and thinner container, children who are younger

than seven or eight years old typically say that the two beakers no longer contain the

same amount of liquid, and that the taller container holds the larger quantity (centration),

without taking into consideration the fact that both beakers were previously noted to

contain the same amount of liquid. Due to superficial changes, the child was unable

to comprehend that the properties of the substances continued to remain the same (conservation).

Irreversibility is a concept developed in this stage which is closely related to the

ideas of centration and conservation. Irreversibility refers to when children are unable to mentally

reverse a sequence of events. In the same beaker situation, the child does not realize

that, if the sequence of events was reversed and the water from the tall beaker was poured

back into its original beaker, then the same amount of water would exist. Another example

of children's reliance on visual representations is their misunderstanding of "less than" or

"more than". When two rows containing equal amounts of blocks are placed in front of a

child, one row spread farther apart than the other, the child will think that the row spread

farther contains more blocks. Class inclusion refers to a kind of conceptual

thinking that children in the preoperational stage cannot yet grasp. Children’s inability

to focus on two aspects of a situation at once inhibits them from understanding the

principle that one category or class can contain several different subcategories or classes.

For example, a four-year-old girl may be shown a picture of eight dogs and three cats. The

girl knows what cats and dogs are, and she is aware that they are both animals. However,

when asked, “Are there more dogs or animals?” she is likely to answer “more dogs”. This

is due to her difficulty focusing on the two subclasses and the larger class all at the

same time. She may have been able to view the dogs as dogs or animals, but struggled

when trying to classify them as both, simultaneously. Similar to this is concept relating to intuitive

thought, known as "transitive inference". Transitive inference is using previous knowledge

to determine the missing piece, using basic logic. Children in the preoperational stage

lack this logic. An example of transitive inference would be when a child is presented