a middle-aged man

psychological development, the development of human beings’ cognitive, emotional, intellectual, and social capabilities and functioning over the course of a normal life span, from infancy through old age. It the subject matter of the discipline known as developmental psychology. Child psychology was the traditional focus of research, but since the mid-20th century much  learned about infancy and adulthood as well. A brief treatment of psychological development follows. For fuller treatment, see human behaviour.

Infancy

Infancy is the period between birth and the acquisition of language one to two years later. Besides a set of inherited reflexes that help them obtain nourishment and react to danger, newborns are equipped with a predilection for certain visual patterns, including that of the human face, and for certain sounds, including that of the human voice. Within a few months they are able to identify their mothers by sight, and they show a striking sensitivity to the tones, rhythmic flow. And individual sounds that make up human speech. Even young infants  capable of complex perceptual judgments involving distance, shape, direction, and depth. And they are soon able to organize their experience by creating categories for objects and events. (e.g., people, furniture, food, animals) In the same way older people do.