Instincts, Motivation, Personality, and Development: A Psychoanalytical Theory

Sigmund Freud is one of the most famous names in psychology, even though most of his ideas have been abandoned by modern psychology his psychoanalytic theory formed the basis for many current psychodynamic theories, Freud was the first to discuss the unconscious mind and its role in human behavior.

Freud believed that there were three levels of consciousness, first is the unconscious mind which exists outside of your awareness at all times, next is the pre conscious mind which includes all information that you're not currently aware of but that can be recalled, finally the conscious mind is your current state of awareness.