This led to Piaget develop four important stages of cognitive development : sensorimotor stage ( birth to age 2 ) , preoperational stage ( age 2 to 7 ) , concrete-operational stage ( ages 7 to 12 ) , and formal-operational stage ( ages 11 to 12 , and thereafter ) .
Sensorimotor Stage The sensorimotor stage is the first stage of Piaget 's theory .