Lt. Col. David Grossman (U.S. Army Ret.), an expert on the psychology of killing, teaches psychology at Arkansas State University, directs the Killology Research Group in Jonesboro, Arkansas, and has written On Killing: The Psychological Cost of Learning to Kill in War and Society. He has coined the term "killology" for a new interdisciplinary field: the study of the methods and psychological effects of training army recruits to circumvent their natural inhibitions to killing fellow human beings.