Jean Piaget (1896-1980) was a Swiss psychologist as well as a biologist. He developed his theory of cognitive development in 1950s. He belonged to a constructivist school of psychology, which believes that learning occurs as a result of the construction of various concepts inside the mind of a child when he/she interacts with his/her environment. His theory is based on the idea that the child builds mental structures; mental maps of the things he/she experiences in his/her environment. These maps initially include some basic and intrinsic reflexes like crying and sucking, but as the child grows and experiences more and more objects/things around him/her, these structures/maps become bigger and more sophisticated. Piaget was of the view that cognitive development of a child is a function of his/her physical development and that physical development precedes learning. It means that the cognitive development of a child is a continuous process, which undergoes various transformations during different points of her age and the child is seen an active participant in this whole process. According to him, cognitive development is a self-automated process, which depends upon the physical and mental maturation of a child. When the child encounters with a physical experience he/she compares it with the experiences already present in his/her mind, if he/she finds that the experience is a repeated one, he assimilates it easily in his/her mind. Conversely, if the experience is a new one, it causes disequilibrium in his/her mind and the child tries to accommodate it in his/her mind. Piaget specified four distinct stages of a child cognitive development; each stage is dependent upon its previous stage. These stages are discussed as under:
- Sensorimotor Stage (Birth to 2 years): During this stage, the child is entirely dependent upon his senses. He/she experiences this world through actions and through his/her senses. He/she is unable to think abstractly. But at the end of this stage the child become able to represent objects with mental images and he/she learns that things exists even they are out of sight, Piaget called it object permanence.
- Preoperational Stage (2 to 7 years): In this stage, the child is still unable to form abstract thought of physical objects. However, he/she can understand this world through language and images. He/she can now represent his ideas through words and sentences. Egocentric thoughts are common during this stage.
- Concrete Operation (7 to 11 years): During this stage, the child starts constructing physical structures and logical thinking. Abstract thinking is also possible during this stage. The child learns to classify things in categories and creates logical relationships between them.
- Formal Stage (11 to 15 years): During this stage, the child starts scientific reasoning and logical thinking like adults. Now, He/she is fully capable to form hypotheses and think systematically and abstractly. He/she becomes able to apply concepts learnt in one context to another.
