Splitting is a term that came out of classical (psychoanalytical or psychodynamic) schools of thought and refers to an unconscious ego defense mechanism by which a fairly complex entity cannot be accepted into consciousness in its entirety because it contains aspects that are both acceptable to a person as well as unacceptable. Relatively underdeveloped personalities, most especially borderline personalities, have a hard time incorporating into consciousness seemingly contradictory aspects of the same person or thing. So, they unconsciously separate or “split” objects into two categories, seeing the “good” side of a person or thing as the part they find acceptable and the “bad” side of the person or thing as the part they find painful or unacceptable. And, it’s much more than just seeing both a good and a bad side to everything. They actually “split” a single entity into two opposing realities, conceptualizing for example a mother who has both a gentle and a terrifying side as alternately “good mommy,” or “bad mommy.” As a result, they will often alternate between over-idealizing and devaluing the same person.