Cognitive distortions are exaggerated or irrational thought patterns that are believed to perpetuate the effects of psychopathological states, especially depression and anxiety. Psychiatrist Aaron T. Beck laid the groundwork for the study of these distortions, and his student David D. Burns continued research on the topic. Most notably, Burns' 1989 book, The Feeling Good Handbook presented information on these thought patterns along with a proposal of how to eliminate them.