On killing. II: The psychological cost of learning to kill.

Military and law enforcement studies reveal that interpersonal combat is a universal human phobia. Physiological responses include forebrain shutdown and sympathetic arousal. A resistance to killing exists in the midbrain of most healthy members of most species, becoming ascendant when the forebrain shuts down, and can prevent soldiers from performing in combat. The U.S. military has increased participation in killing activities from 20% in World War II to 95% in Vietnam by operantly conditioning responses. Conditioning is achieved through training that closely resembles battle situations and inadvertently occurs when children see violence as entertainment. The price of this conditioning is an increase in post-traumatic stress disorder which can be defrayed through debriefing, social acceptance, and prevention of atrocities. Similar techniques may be used to prevent PTSD in civilian populations involved in tragedies like school shootings.