Physical aggression as a function of strength of frustration and instrumentality of aggression

Direct physical aggression was related to three variables through a modification of the Buss (1961) “aggression machine” and procedure. There were two intensities of frustration and a control group established on the basis of the goal gradient principle. Aggression was either instrumental or noninstrumental in overcoming the frustration. Frustration was arbitrary (unreasonable) or nonarbitrary (reasonable). More aggression occurred under the instrumental condition than under the noninstrumental condition. The stronger frustration produced more aggression than the weaker frustration, but only when aggression had previously been experienced as instrumental. No more aggression occurred under the arbitrary frustration condition than under the nonarbitrary condition. The results were discussed in relation to the frustration-aggression hypothesis and the goal gradient principle.