One of the foundational ideas in developmental psychology comes from Jean Piaget, who described the earliest stage of human learning as the sensorimotor stage. His observation was simple but profound: We learn by interacting with the world through our bodies. Before children can reason abstractly, they build understanding through movement and sensory exploration — grasping objects, crawling across spaces, turning things over, testing cause and effect. Knowledge is constructed through doing. In o

Cognitive Development Theories of Jean Piaget.