Early psychology was considered a science that dealt with the causes and treatment of mental illness. Famed psychologist such as Sigmund Freud worked with neurotic and psychotic patients. His theories of psychoanalysis and resulting model of mental structure were based on his work with his patients and his own inner struggles. Freud’s own life experiences wielded one of the strongest influences on his theory of personality.

But psychology based on one person’s experiences is not enough. U.S. Air Force Personnel Laboratory became involved in developing a model to show the broad spectrum of people’s personalities in the 1960s. Ernest Tupes and Raymond Christal developed the Five Factor Model of personality. They reviewed other’s research to find a set of traits that would form this model. Still they clung to the idea of psychology showing the differences between healthy and unhealthy traits. The names that they gave each factor–Surgency…