Flight-elicited attack and priming of aggression in nonaggressive hamsters

We report a technique for inducing attack in apparently nonaggressive hamsters that takes advantage of several behavioral effects: (a) the vigorous flight that repeatedly defeated hamsters display in the presence of conspecifics, (b) the potent, attack-eliciting properties of such flight, and (c) attack priming (i.e., aggressive arousal from exposure to an initial stimulus animal carries over to exposure to a second one). Resident hamsters that had consistently failed to attack nonfleeing intruders were found to readily attack intruders that did flee. But repeated exposure to the fleeing intruders alone did not induce long-term changes in aggressiveness. However, flight-elicited attack did successfully prime attack onto nonfleeing intruders presented immediately after the fleeing intruder was removed. Repeating such priming transfer trials induced long-term changes in the formerly nonaggressive subjects. We conclude that this is an effective procedure for inducing aggression that would be preferred when it is important to avoid exposing subjects to aversive stimuli. The changes in behavior that we observed seem to reflect heightened motivational levels.