Thomas, M. H., et al. (1977). Desensitization to portrayals of real-life aggression as a function of exposure to television violence. Journal of Personality and Social Psychology, 35 (6), 450-458.

Abstract:  Tested in 2 separate experiments, the hypothesis that exposure to violence in the context of TV drama decreases Ss’ emotional responsivity to portrayals of real-life aggression. Ss were shown either an excerpt from a violent police drama or a segment of an exciting but nonviolent volley-ball game before watching a videotaped scene of real aggression. Emotionality was measured by changes in skin resistance which was measured continuously throughout the session. In Exp I, Ss were 28 8-10 yr olds, and the real aggression was a film of an argument and fight between 2 preschoolers. In Exp II, 59 college students participated, and reactions to real aggression were measured while Ss watched scenes from news films of the riots at the 1968 Democratic National Convention. With the exception of adult females, Ss who previously had viewed the aggression drama were less aroused by the scenes of real aggression than were Ss who had seen the control film. The hypothesis is further supported by the finding that for most groups of Ss, the amount of TV violence normally viewed was negatively related to responsivity while viewing aggression. (17 ref) (PsycINFO Database Record (c) 2004 APA, all rights reserved)