Building on the theoretical models of Jean Piaget regarding child development, psychologist David Elkind developed his own theory of adolescent egocentrism, or the general difficulty adolescents have in separating their own mental and emotional preoccupations from those of others. This level of egocentrism, he posited, impacted a child's emotional development, behavior, and thought.
When young people undergo the various physiological changes that come with adolescence, they often become preoccupied with themselves and these changes. Because they are so focused on themselves, they naturally assume that others are, as well. This mistaken assumption of others' thoughts and opinions leads them to anticipate how others will react to them and how they will subsequently react to others; this imaginary audience they have created by way of their focus on others' perceptions of themselves is the focus of their thoughts, emotions, and energies.
As time passes and the child matures into adulthood, they come to learn that others are not as preoccupied with them as they themselves are. The self-consciousness that is so common in adolescence begins to dissipate as they develop the emotional and behavioral maturity to be less concerned with others' thoughts and opinions and instead seek their own validation. This transition out of Elkind's theory of adolescent egocentrism marks a successful progression into adulthood.