Aaron Temkin Beck was an American psychiatrist who was a professor in the department of psychiatry at the University of Pennsylvania. He is regarded as the father of cognitive therapy and cognitive behavioral therapy (CBT). His pioneering methods are widely used in the treatment of clinical depression and various anxiety disorders. Beck also developed self-report measures for depression and anxiety, notably the Beck Depression Inventory (BDI), which became one of the most widely used instruments for measuring the severity of depression. In 1994 he and his daughter, psychologist Judith S. Beck, founded the nonprofit Beck Institute for Cognitive Behavior Therapy, which provides CBT treatment and training, as well as research. Beck served as President Emeritus of the organization up until his death.

Martin Elias Peter Seligman is an American psychologist, educator, and author of self-help books. Seligman is a strong promoter within the scientific community of his theories of well-being and positive psychology. His theory of learned helplessness is popular among scientific and clinical psychologists. A Review of General Psychology survey, published in 2002, ranked Seligman as the 31st most cited psychologist of the 20th century.