The child inherits all the sensory equipment that is needed for mental activity. The child shows evidence of his thinking ability at a very early age. For example, he tries to secure approval from his parents for the things he likes or does. The child’s curiosity is another characteristic of mental development at this stage. He is curious to know about his immediate environment. He also develops the ability to differentiate people and things around him.

According to Jean Piaget, this is the stage of sensory motor activity, the first level in his scheme of Cognitive Development. During this period, the infant’s actions are not yet internalized in the form of thoughts. The infant exercises sensor motor capacities by sucking, handling or by moving objects.

He behaves as if objects that have disappeared from view have ceased to exist. “Out of sight, out of mind” might be said to characterise the view of the infant. For example, Piaget tells us that an infant of five to eight months of age, already old enough to seize a solid object, will lose interest and turn away if a cloth be thrown over the object before his hand reaches it.

At a slightly older age, he is capable of seeking an object behind a screen. This is the beginning of the notion that objects have permanent exteriors, and that they are there in the world, independent of him. However, at this stage, the child’s intelligence level is equal to that of intelligent animals.