90 male college students were either attacked or treated in a more neutral manner by a male confederate. On a subsequent maze-learning task, 30 Ss shocked the confederate, 30 observed as the E shocked the confederate, and 30 waited for a period of time during which the confederate was not shocked. Finally, all Ss shocked the confederate as part of a code-learning task. Ss who had been attacked and had shocked the confederate during the maze task delivered shocks of greater intensity on the code task than did Ss in the other 2 conditions, and the former Ss also experienced a greater reduction in diastolic blood pressure than did the latter. Results contradict the hypothesis of aggression catharsis and are discussed in terms of feelings of restraint against aggressing that an S experiences after committing an aggressive act. (19 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)