Final answer:
The sensorimotor stage is the first stage in Piaget's theory of cognitive development, where children learn about the world through their senses and motor behavior. Object permanence and motor development are important milestones during this stage.
Step-by-step explanation:
The sensorimotor stage is the first stage in Piaget's theory of cognitive development, which lasts from birth to about 2 years old. During this stage, children learn about the world through their senses and motor behavior. They explore their environment using their senses and learn through actions such as putting objects in their mouths or shaking and banging them to see if they make sounds.
Object permanence is a key milestone during this stage, where infants develop the understanding that even if something is out of sight, it still exists. Young infants may not remember an object after it has been removed from sight, whereas infants who have developed object permanence will reach for the hidden toy, indicating their awareness of its existence.
Motor development also occurs during this stage, with infants progressing from reflexive reactions to more advanced motor skills like holding their heads up, sitting with assistance, crawling, and walking.