 Cognitive psychologists offered theories on depression in the mid-twentieth century.Starting in the 1950s, Albert Ellis argued that depression stemmed from irrational "should" and "musts" leading to inappropriate self-blame, self-pity, or other-pity in times of adversity.Starting in the 1960s, Aaron Beck developed the theory that depression results from a "cognitive triad" of negative thinking patterns, or "schemas," about oneself, one's future, and the world.