ACT, dialectical behavior therapy (DBT), functional analytic psychotherapy (FAP), mindfulness-based cognitive therapy (MBCT) and other acceptance- and mindfulness-based approaches are commonly grouped under the name "the third wave of cognitive behavior therapy". The first wave, behaviour therapy, commenced in the 1920s based on Pavlov's classical (respondent) conditioning and operant conditioning that was correlated to reinforcing consequences. The second wave emerged in the 1970s and included cognition in the form of irrational beliefs, dysfunctional attitudes or depressogenic attributions. In the late 1980s empirical limitations and philosophical misgivings of the second wave gave rise to Steven Hayes' ACT theory which modified the focus of abnormal behaviour away from the content or form towards the context in which it occurs. ACT research has suggested that many of the emotional defenses individuals use with conviction to try to solve their problems actually entangle humans into greater suffering. Rigid ideas about themselves, lack of focus on what is important in their life and struggling to change sensations, feelings or thoughts that are troublesome only serve to create greater distress.