I believe that one of the most prominent psychologists of the twentieth century would be Jean Piaget. Piaget's cognitive theory developed from the theory that focuses on the structure and development of thinking, which shapes people's attitudes, beliefs, and behaviors (Berger, 2005). I will explain his theory, in detail and give explanation why I feel this is one of the most notable grand theories.
The sensorimotor stage lasts form birth until two years of life. During this period, "the infant's movements, physical and intellectual lack precision and her activities and attention are dominated by external stimulation."(Sigel & Cocking). Piaget viewed this as a completely physical stage in which children depend almost entirely on their physical senses: sight, taste, touch, and hearing. . The sensorimotor stage, like Piaget's other stages, give emphasis to the fact that our makeup and personality are inborn, by de-emphasizing parental influence.
Piaget's second developmental stage is the preoperational stage.
This stage continues from age 2 until age 6. "It is not until the second stage, preoperations, that children have mental representations of object, independent of actions on the objects." (Small). Through this time children will represent things with words and images. But, they don't have the reasoning skills to analyze higher concepts. An important cause of this is Piaget's theory that, "the child is egocentric, using herself as the standard of judgment and unable to take the viewpoints of other people"(Sigel & Cocking). The presences of these characteristics are born with, and therefore normal to, the human being.
Logical thinking begins to take place during the third stage of Piaget's theory of cognitive development, the concrete operational stage. "The stage of concrete operations is defined by the ability to operate on and systematically manipulate these mental representation" (Small). The logic gained during ages 7...