|Substage One: Simple Reflexes
|Birth to 1 month
|This active learning begins with automatic movements or reflexes. A ball comes into contact with an infant’s cheek and is automatically sucked on and licked.
|Substage Two: Primary Circular Reactions
|1 to 4 months
|The infant begins to discriminate between objects and adjust responses accordingly as reflexes are replaced with voluntary movements. An infant may accidentally engage in a behavior and find it interesting such as making a vocalization. This interest motivates trying to do it again and helps the infant learn a new behavior that originally occurred by chance. At first, most actions have to do with the body, but in months to come, will be directed more toward objects.
|Substage Three: Secondary Circular Reactions
|4 to 8 months
|The infant becomes more and more actively engaged in the outside world and takes delight in being able to make things happen. Repeated motion brings particular interest as the infant is able to bang two lids together from the cupboard when seated on the kitchen floor.
|Substage Four: Coordination of circular reactions
|8 to 12 months
|The infant can engage in behaviors that others perform and anticipate upcoming events. Perhaps because of continued maturation of the prefrontal cortex, the infant becomes capable of having a thought and carrying out a planned, goal-directed activity such as seeking a toy that has rolled under the couch. The object continues to exist in the infant’s mind even when out of sight and the infant now is capable of making attempts to retrieve it.
|Substage Five: Tertiary Circular Reactions
|12 to 18 months
|The infant more actively engages in experimentation to learn about the physical world. Gravity is learned by pouring water from a cup or pushing bowls from high chairs. The caregiver tries to help the child by picking it up again and placing it on the tray. And what happens? Another experiment! The child pushes it off the tray again causing it to fall and the caregiver to pick it up again!
|Substage Six: Internalization of Schemes and Early Representational thought
|18 months to 2 years