Cognitive development in infancy

Piagets
In Piaget's theory of cognitive developmentthe period of infancy is covered within what he called the sensoimotor period

Infants are born with a set of congenital reflexes, according to Piaget, in addition to a drive to explore their world. Their initial schemas are formed through differentiation of the congenital reflexes The sensorimotor period is the first of the four periods. According to Piaget, this stage marks the development of essential spatial abilities and understanding of the world in six sub-stages:
 * 1) The first sub-stage, known as the reflex schema stage, occurs from birth to six weeks and is associated primarily with the development of reflexes.
 * 2) The second sub-stage, primary circular reaction phase, occurs from six weeks to four months and is associated primarily with the development of habits.
 * 3) The third sub-stage, the secondary circular reactions phase, occurs from four to nine months and is associated primarily with the development of coordination between vision and prehension.
 * 4) The fourth sub-stage, called the co-ordination of secondary circular reactions stage, which occurs from nine to twelve months, is when Piaget (1954) thought that object permanence developed.
 * 5) The fifth sub-stage, the tertiary circular reactions phase, occurs from twelve to eighteen months and is associated primarily with the discovery of new means to meet goals.
 * 6) The sixth sub-stage, considered "beginnings of symbolic representation", is associated primarily with the beginnings of insight, or true creativity.