what are the four stages of cognitive development proposed by piaget
Piaget's theory of cognitive development In his theory of Cognitive development, Jean Piaget proposed that humans progress through four developmental stages: the sensorimotor, preoperational, concrete operational and formal operational period.[20] The first of these, the sensorimotor stage "extends from birth to the acquisition of language."[21] In this stage, infants progressively construct knowledge and understanding of the world by coordinating experiences (such as vision and hearing) with physical interactions with objects (such as grasping, sucking, and stepping).[22] Infants gain knowledge of the world from the physical actions they perform within it.[23] They progress from reflexive, instinctual action at birth to the beginning of symbolic thought toward the end of the stage.[23]
Phonological development Even though children do not produce their first words until they are approximately 12 months old, the ability to produce speech sounds starts to develop at a much younger age. Stark (1980) distinguishes five stages of early speech development:[16]