For example, a child in northern Switzerland might grow up learning and knowing German, then travel west and find himself in a French-speaking community. At this point, developing children will realize that their language, their culture, everything they have learned about, all their experiences in language and communication will be completely different from someone else's in a another life. Piaget (1952) describes this experience as "disequilibrium" in his Cognitive Theory and is a fundamental part of one of the four stages of cognitive development. Although this theory focuses primarily on learning experiences such as mathematics and physical effects, it also translates into language as this state of imbalance gives the child the opportunity to both experience different cultures and languages, as well as learn more about their own life.