Cognitive-behavioral therapies work to achieve a therapeutic change of a given maladaptive behavior/ symptom by revealing the cognitions (thoughts, evaluations, judgments) that underlie them. The role of the meaning given to the individual by an event and the evaluation processes are demonstrated by R. Lazarus, who finds that it is not the stimulus itself that has a stressful effect, but the evaluation, interpretation and expectations of people are what determine their physiological and behavioral reactions.
Cognitive therapies aim to correct unrealistic perceptions and misinterpretations. They look for the causes of dysfunction in defects of cognitive processes, selective attention to tendentious inferences and failure to take into account positive experiences.
In the early 1960s, Albert Ellis formulated the model of the first cognitive therapy, which he called Rational-Emotional Therapy. According to Ellis, what leads to emotional distress and problems in adaptation is the acquisition of irrational beliefs and distorted cognitions, which are triggered in response to a certain activating event and cause a negative emotional response and neurotic symptoms. PET uses a rich palette of clinical techniques, including self-observation, debate, role-playing games, modelling and more.
Aaron Beck's therapeutic approach also emerged in the 1960s. In his clinical work with depressed patients, Beck began to notice a consistent pattern of conscious negative thoughts about themselves, the world, and the future, which he called the "cognitive triad" of depression. To restructure depressive cognitions, Beck uses a number of behavioral techniques, e.g. planning pleasant activities. As with PET, most of the behavioral tasks in cognitive therapy are conducted to test clients' fundamental beliefs.
Source: Comprehensive Textbook of Psychotherapy: Theory and Practice, Edited by Bongar, B. and Beutler, E.