In the first two years of life, infants undergo a series of rapid cognitive developments. Jean Piaget, a Swiss psychologist, developed a theory of development to describe this process. His theory includes four stages: the sensorimotor, preoperational, concrete operational, and formal operational periods. Infants from birth to 24 months are in Piaget's sensorimotor stage of development. Important cognitive developments during this period include object permanence, spatial knowledge, understanding of causality, number and categorization sense, and imitation.
Simple Reflexes
The use of simple reflexes is the first substage of Piaget's sensorimotor period. In this substage, infants from birth to 1 month of age begin to coordinate their inborn reflexes. These reflexes include the sucking and the grasping reflex. As the infant develops, these reflexes start to become voluntary.
Primary Circular Reactions
In this substage, babies who are between 1 and 4 months of age begin to repeat pleasurable behaviors. These behaviors begin as reflexes, and babies learn to control them and repeat them at will. An infant who begins to suck his thumb has undergone a primary circular reaction. Babies at this stage also begin to coordinate their vision and hearing by turning toward sounds.
Secondary Circular Reactions
Babies between 4 and 8 months of age begin to understand the concept of causality. Infants begin to extend their focus beyond their own bodies to objects in the environment. They will repeat actions for the sake of bringing about interesting results with these objects. For example, a baby at this stage may shake a rattle to hear the sound it makes. As babies become mobile, they also begin to gain spatial knowledge.
Coordination of Secondary Circular Reactions
Between 8 and 12 months of age, babies begin to display intentional, goal-oriented behaviors. For example, babies in this substage will crawl toward objects of interest and may choose certain toys over others. The concept of object permanence begins to develop as well, and babies understand that objects exist even when they are out of sight. It is for this reason that babies this age enjoy the game of peek-a-boo.
Tertiary Circular Reactions
Babies from 12 to 18 months of age begin to use problem-solving skills. They will display tertiary circular reactions, meaning that they will change their actions to get desired results and will experiment with novel behaviors. For example, a baby at this stage of development will try different ways to get a toy to work the right way.
Mental Combinations
In the sixth and final substage of the sensorimotor period, babies between 18 and 24 months begin to develop number and categorization sense and can imitate behaviors after an extended time. Toddlers at this age display symbolic thought and representation ability, meaning they can store images and symbols of objects and events in their memories. They can also repeat behaviors they have seen in the past, leading to pretend play. By 2 years of age, babies begin to move out of the sensorimotor period and into the preoperational period of development.
References
- A Child's World: Infancy Through Adolescence (updated 9th ed.); Diane Papalia, Sally Olds, Ruth Feldman; 2004
- The Psychology of the Child; Jean Piaget; 1972
