Personality psychology studies how people think, feel, and behave (the psychological triad). It overlaps with clinical psychology in studying both normal and extreme patterns of personality. The goal of personality psychology is to explain the whole person in their daily environment, though this is very difficult. There are multiple basic approaches to studying personality, including traits, biology, psychoanalysis, learning, and cognition. While each approach has strengths and weaknesses, they are not mutually exclusive and can provide complementary perspectives on understanding personality.