Summarize Piaget's theory of cognitive development.
Piaget argued that cognitive development occurred in four distinct stages. The first was a sensory motor stage, which occurred in the first two years of life. In this stage, babies learn through the consequences their physical actions, which include grabbing, sucking, eating, and so on. The second stage is what Piaget called a "preoperational" or intuitive phase. During this phase, the use of language allows a child to interact with the world, and thus to learn, in a variety of ways. But children at this stage are still essentially self-centered in that they can only really understand the world as they interact with it; they are incapable of empathy. The third phase is a "concrete operational" phase, and it lasted from age seven to about eleven. During this phase, though again, children were centered on their own world, and their own actions, they became aware of the ways their actions are organized into categories. In other words, they start to understand abstract concepts like division, multiplication, word grouping, or other cognitive strategies. This paves the way for the fourth stage, in which children become capable of deduction and problem-solving. The important thing to note here is that although Piaget believed that these stages were natural, stemming from inborn, instinctive developmental "hardwiring" in the early stages, the speed and the success with which children progressed intellectually depended in large part on the extent to which these skills (like problem solving, grouping, and so on) were nurtured in their education.