Subconscious, a popular term for a person's mental activity of which he or she is not aware. It usually refers to the preconscious, defined by psychoanalyst Sigmund Freud as mental activity that is just below the level of awareness and can easily be brought into consciousness. Sometimes “subconscious” is used also to refer to the unconscious, Freud's term for mental activity that can be brought to consciousness only by great effort and by the use of such techniques as free association or hypnosis. The preconscious and the unconscious affect behavior and personality, influencing everyday thoughts and acts. The unconscious is the basis for such mental disorders as hysteria and the various phobias.