Cognitive Therapy (CT) is a type of psychotherapy eveloped by psychiatrist Aaron T. Beck in the 1960s. Becoming disillusioned with long-term psychodynamic approaches based on gaining insight into unconscious emotions and drives, Beck came to the conclusion that the way in which his clients perceived and interpreted and attributed meaning—a process known scientifically as cognition—in their daily lives was a key to therapy.Albert Ellis was working on similar ideas from a different perspective, in developing his rational emotive behaviour therapy (REBT). Beck initially focused on depression and developed a list of "errors" in thinking that he proposed could cause or maintain depression, including arbitrary inference, selective abstraction, over-generalization, and magnification (of negatives) and minimization (of positives). Cognitive therapy seeks to identify and change "distorted" or "unrealistic" ways of thinking, and therefore to influence emotion and behaviour.