Zillmann, D., & Weaver, J. B. III. (1999). Effects of prolonged exposure to gratuitous media violence on provoked and unprovoked hostile behavior. Journal of Applied Social Psychology, 29 (1), 145-165.

Abstract:  On 4 consecutive days, respondents were exposed to gratuitously violent or nonviolent intact feature films. They rated the entertainment value of these films. One day after exposure to the last film of the series, respondents participated in ostensibly unrelated research on emotion recognition. As they performed a test, they were neutrally or abusively treated by a research assistant. Thereafter, they were put in a position to harm this assistant. Both provocation and exposure to violent films were found to foster markedly increased hostile behavior. These effects were noninteractive. Moreover, these effects were uniform for respondent gender. Compared to men, women exhibited less hostility overall, however. The findings thus show that prolonged exposure to gratuitously violent films is capable (a) of escalating hostile behavior in provoked men and women, and (b) perhaps more importantly, of instigating such behavior in unprovoked men and women. (PsycINFO Database Record (c) 2004 APA, all rights reserved)