Jean Piaget, a Swiss cognitive theorist who believed that children's learning depended on reinforcers, such as rewards from adults. According to his theory of cognitive development, children actively construct knowledge as they explore their world (Berk, 2008). Piaget divided cognitive development into 4 main phases which he called sensorimotor, pre-operational, concrete operational and formal operational. According to Piaget this sequence is invariant; all children will progress through the stages in the same order. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay During the sensorimotor stage, from birth until approximately 18-24 months, children are not yet able to use symbols or images to represent objects in external world space (Essa, 2009). To think about an object they must act on it with their senses and motor skills. The main advancement of this stage is object permanence, the understanding that objects continue to exist outside of sensory awareness. If a child picks up a toy and you cover it with a cloth, he or she will stop grabbing it and look at something else. If you secretly remove the toy and then lift the cloth, the child will look at the empty space without surprise or disappointment. According to Piaget, the child does not yet possess object permanence; Out of sight is out of mind. By one year of age, infants develop object permanence and can use mental representation and think about objects that are not physically present. From approximately 2 to 7 years of age, the child is in the pre-operational stage of development. Now they can use mental representation to think. They begin to use pretend play. Children are now capable of symbolic representation – using a symbol to represent an object (Berk, 2008). This is why children learn language, a system of symbols. Piaget emphasized that during this period children's abilities are limited. A pervasive limitation of children's reasoning during the preoperational period is egocentrism, the inability to take another person's perspective. A child may assume that everyone has the same knowledge, experiences, and perspectives that he or she does. Egocentric thinking predominates. The concrete operational phase lasts approximately 7 to 11 years. Children can now engage in mental representation and think logically about the world around them (Essa, 2009). Specifically, children are able to manipulate their mental representations to think and solve problems. Thinking becomes logical, overcoming the limits of the pre-operational phase of reasoning. Children are now able to understand conservation, that a change in the size and shape of a substance (such as clay) does not change its mass. Operational thinking (reversible mental actions) develops. Egocentric thinking decreases. During early adolescence, individuals enter Piaget's period of formal operations. Now cognitive development reaches its peak. Adolescents become capable of using and manipulating their symbolic representations in abstract thinking. They can create and think logically through hypothetical situations. Scientific and deductive reasoning becomes possible. The individual is cognitively mature. At the beginning of the period there is a return to egocentric thinking. Only 35% of high school graduates in industrialized countries obtain formal operations; many people do not think formally during adulthood (Interactive Educational Psychology). Please note: this is just an example. Get a customized document from our writers now.