Perry, D. G., & Perry, L. C. (1976). Identification with Film Characters, Covert Aggressive Verbalization, and Reactions to Film Violence. Journal of Research in Personality, 10 (4), 399-409.

Abstract:  To determine some conditions governing the aggressive aftereffects of identification with aggressive film characters, 108 male undergraduates were 1st angered by a confederate and then exposed to a film clip of a violent boxing match. Ss instructed to identify with the winner of the prize fight were subsequently more aggressive toward the confederate than Ss instructed to identify with the loser or Ss not asked to identify with a film aggressor. Apparently, viewers must perceive their identificand incur reinforcement for aggression before they become more aggressive themselves. However, requiring Ss to make implicit aggressive verbalizations during the film completely eliminated any aggressive aftereffects of identification. This finding was unexpected and suggested that covert verbalization interfered with Ss’ ability to make the vicarious aggressive responses which mediate increased subsequent aggression. (PsycINFO Database Record (c) 2004 APA, all rights reserved)