Humanistic psychology is theory, research, and practice that embrace's the belief that a person should be viewed as a whole, not merely the sum of their parts. This entails the incorporation of mind, body, and spirit in unity as a person experiences the world. Humanistic psychology values the individual as an experiencing being, with the belief that experience and awareness is essential to understanding people. There is value in the unspoken dimensions of the persons: feelings, intuition, creativity, and imagination are meaningful elements that contribute to the uniqueness of being human. The practice of a humanistic psychologist is guided by a belief that human beings have choice, and with choice comes responsibility. The following are some basic viewpoints from the Sanford Encyclopedia of Philosophy, with which most humanistic psychologists agree; a person does not live alone, people are social by nature and their interpersonal interactions are a part of their development, a person has free will, people are aware of themselves; therefore they can make conscious choices. Humanistic psychology centers on the development of a person. There are three key components of reaching the highest level of self-understanding and development: self-actualization, self-fulfillment, and self-realization. There are different perspectives on how to reach each of these stages. Carl Rogers believed a full self-understanding could be achieved if a person learned how to trust his or her own judgment and feelings. Abraham Maslow believed that the way of reaching self-understanding was by first satisfying lower needs. The end agreement is that no matter how self-understanding is reached, it will result in giving a person the ability to make better choices for themselves.
A major aspect of psychology called behaviorism developed from research on learning. The American psychologist John B. Watson introduced behaviorism in 1913; he felt psychologists should study only observable behavior rather than states of consciousness or thought processes.