One of the famous psychologist named Jean Piaget has proposed the theory of cognitive development in which he has mentioned four different stages of human development that occurs through different phases in an individual's life.
Formal operational stage: The formal operational stage is the fourth stage in the cognitive development theory. This stage begins with the age of approximately eleven to fifteen years and lasts through adulthood. As an adolescent enters in this stage, he or she acquires the ability to think abstractly by manipulating different ideas in his or her mind without being dependent on concrete manipulation.
