A baby's intellectual development progresses through distinct stages as he adjusts to life outside of the womb. The progression of intellectual development in babies has been studied for centuries, but one of the most widely accepted models is Jean Piaget's (1896-1980) four cognitive stages of development, according to PBS.org. The sensorimotor stage lasts from birth through 18 months and is split into six individual substages because so many changes occur in such a short period.
All babies are born with reflexes that help them understand and interact with their surroundings. Babies will suck on a nipple or pacifier if placed next to their mouth. They will also wrap their fingers around an object placed in the palm of their hand. A baby modifies these reflexes as he adapts to his environment, such as being able to distinguish between a nipple on a bottle or another object. This stage lasts from birth until a baby is 1 month old.
Primary Circular Reactions
The second stage, which lasts from 1 month until 4 months, is the development of primary circular reactions, according to a 2008 research paper titled "Piaget's Sensorimotor Stage," published by Pearson Education Inc. Babies learn to move their hand to and from their mouth or to objects around them. Then they repeat these behaviors. This stage is where babies begin to act intentionally.
Secondary Circular Reactions
The third substage is the secondary circular reaction stage, which lasts from 4 to 8 months of age, according to "Piaget's Sensorimotor Stage." Piaget recognized that children become more aware of their environment and know that these behaviors have the ability to directly affect the objects around them. They tend to be fascinated by their actions such as dropping a spoon and realizing they no longer have it in their hands.
Coordination of Secondary Circular Reactions
The fourth stage of development is Coordination of Secondary Circular Reactions. Babies begin to understand the concept of cause and effect. Their actions become more intentional as they begin to engage in goal-directed behavior, such as reaching for a string that is out of reach. Piaget theorized that children develop the concept of object permanence, which is the realization that objects still exist, even if they are not in sight, during this stage. This stage lasts from 8 to 12 months of age.
Tertiary Circular Reactions
The Tertiary Circular Reactions stage lasts for a period of six months, from the age of 12 months to 18 months. Babies get to exercise their flexibility and creativity as they experiment with objects to achieve new outcomes. They will go from hitting the floor with a spoon to tapping on the wall.
Mental representation is the last substage in Piaget's sensorimotor stage and lasts from 18 to 24 months, according to "Piaget's Sensorimotor Stage." They move from experimenting through trial-and-error to mental planning and predicting outcomes from their actions. This is also when imitation begins as children watch and mimic other peoples' actions hours or days later after first seeing it.