Beck is noted for his research in psychotherapy, psychopathology, suicide, and psychometrics. He has published more than 600 professional journal articles, and authored or co-authored 25 books. He has been named one of the "Americans in history who shaped the face of American Psychiatry", and one of the "five most influential psychotherapists of all time" by "The American Psychologist" in July 1989. His work at the University of Pennsylvania inspired Martin Seligman to refine his own cognitive techniques and later work on learned helplessness.