The influence of dualism on early psychology provided a temptingly simple answer to the question of why people behave as they do. Because dualist views of human nature supported the idea of free will, the dualist 'theory' of motivation succinctly asserted that people choose their courses of action.
This view presented problems for scientific psychologists, especially as research identified indisputable environmental influences on behavior. Given the mechanistic influences on early psychology, a more appealing theory of motivation explained human behavior as being, like animal behavior, governed by instincts. Instincts are innate, goal-directed sequences of behavior; they are more complex than simple reflexes but are impervious to the influence of learning and experience.