<P> Children learn that they are separate from the environment . They can think about aspects of the environment, even though these may be outside the reach of the child's senses . In this stage, according to Piaget, the development of object permanence is one of the most important accomplishments . Object permanence is a child's understanding that objects continue to exist even though he or she cannot see or hear them . Peek - a-boo is a good test for that . By the end of the sensorimotor period, children develop a permanent sense of self and object . </P> <P> Piaget divided the sensorimotor stage into six sub-stages ". </P> <Table> <Tr> <Th> Sub-Stage </Th> <Th> Age </Th> <Th> Description </Th> </Tr> <Tr> <Td> 1 Simple reflexes </Td> <Td> Birth - 6 weeks </Td> <Td> "Coordination of sensation and action through reflexive behaviors". Three primary reflexes are described by Piaget: sucking of objects in the mouth, following moving or interesting objects with the eyes, and closing of the hand when an object makes contact with the palm (palmar grasp). Over the first six weeks of life, these reflexes begin to become voluntary actions . For example, the palmar reflex becomes intentional grasping . </Td> </Tr> <Tr> <Td> 2 First habits and primary circular reactions phase </Td> <Td> 6 weeks - 4 months </Td> <Td> "Coordination of sensation and two types of schema: habits (reflex) and primary circular reactions (reproduction of an event that initially occurred by chance). The main focus is still on the infant's body". As an example of this type of reaction, an infant might repeat the motion of passing their hand before their face . Also at this phase, passive reactions, caused by classical or operant conditioning, can begin . </Td> </Tr> <Tr> <Td> 3 Secondary circular reactions phase </Td> <Td> 4--8 months </Td> <Td> Development of habits . "Infants become more object - oriented, moving beyond self - preoccupation; repeat actions that bring interesting or pleasurable results". This stage is associated primarily with the development of coordination between vision and prehension . Three new abilities occur at this stage: intentional grasping for a desired object, secondary circular reactions, and differentiations between ends and means . At this stage, infants will intentionally grasp the air in the direction of a desired object, often to the amusement of friends and family . Secondary circular reactions, or the repetition of an action involving an external object begin; for example, moving a switch to turn on a light repeatedly . The differentiation between means and ends also occurs . This is perhaps one of the most important stages of a child's growth as it signifies the dawn of logic . </Td> </Tr> <Tr> <Td> 4 Coordination of secondary circular reactions stages </Td> <Td> 8--12 months </Td> <Td> "Coordination of vision and touch--hand - eye coordination; coordination of schemas and intentionality". This stage is associated primarily with the development of logic and the coordination between means and ends . This is an extremely important stage of development, holding what Piaget calls the "first proper intelligence". Also, this stage marks the beginning of goal orientation, the deliberate planning of steps to meet an objective . </Td> </Tr> <Tr> <Td> 5 Tertiary circular reactions, novelty, and curiosity </Td> <Td> 12--18 months </Td> <Td> "Infants become intrigued by the many properties of objects and by the many things they can make happen to objects; they experiment with new behavior". This stage is associated primarily with the discovery of new means to meet goals . Piaget describes the child at this juncture as the "young scientist," conducting pseudo-experiments to discover new methods of meeting challenges . </Td> </Tr> <Tr> <Td> 6 Internalization of schemas </Td> <Td> 18--24 months </Td> <Td> "Infants develop the ability to use primitive symbols and form enduring mental representations". This stage is associated primarily with the beginnings of insight, or true creativity . This marks the passage into the preoperational stage . </Td> </Tr> </Table> <Tr> <Th> Sub-Stage </Th> <Th> Age </Th> <Th> Description </Th> </Tr>

What is piaget's third stage of cognitive development
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