Leyens, J.-P., Camino, L., Parke, R. D., & Berkowitz, L. (1975). Effects of movie violence on aggression in a field setting as a function of group dominance and cohesion. Journal of Personality and Social Psychology, 32 (2), 346-360.

Abstract:  In a quasi-experimental field study, 85 high-school age delinquent boys in a residential facility viewed aggressive or neutral commercial movies every evening for a week. Behavioral observations were obtained through a non-hierarchical, minimally inferential time-sampling procedure during a baseline week (at noon and in the evening), a treatment week (noon and evening), and a posttreatment week (noon). The main immediate effects of the violent films were an overall increase of both active behaviors and physical aggression; the effects on verbal aggression were more persistent but limited to 1 of the 2 cottages of Ss viewing aggressive films. On the other hand, more interactions occurred as an immediate consequence of viewing the films in the 2 neutral treatment cottages; moreover, 1 of these 2 cottages also decreased its level of physical (short-term effect) and verbal (short- and long-term effects) aggression. In the aggressive treatment cottage, which was most affected, Ss who were most dominant, most popular, and least popular were influenced the most; an opposite effect was exhibited by Ss who were judged as least aggressive by their peers. (27 ref) (PsycINFO Database Record (c) 2004 APA, all rights reserved)