Attack priming and satiation in female golden hamsters: Tests of some alternatives to the aggression arousal interpretation

“Priming” a female hamster by allowing it a single attack on an intruder placed into its home cage transiently decreases the latency and increases the probability of attack on a second trial. Although we have previously argued that this priming effect reflects an increase in aggressive arousal, an alternative interpretation is that the fear elicited by placing a foreign object into the subject's home cage is reduced when it happens again on the second trial. Another interpretation is that priming is an effect of intruder novelty, i.e., the subject perceives a difference between the first and second intruders which causes it to attack the second more quickly. Experiment 1 compared the standard two trial paradigm with different intruders to trials in which (1) the first intruder was withdrawn and used again in the second trial, and (2) the intruder remained in the cage following the first attack. All intruders were pretreated with the analgesic‐sedative methotrimeprazine to reduce the variability of their behavior. Neither hypothesis tested in Experiment 1 was supported, strengthening the interpretation of attack priming as a manipulation that affects primarily internal motivational mechanisms specific to aggression. Allowing a hamster to carry out a protracted series of attacks produces a “satiation” effect that is the reverse of priming, i.e., the latency of a subsequent attack is increased and its probability reduced. It is possible that the attack satiation observed in our earlier studies was not the result of processes internal to the subject, but could have been due to habituation to a particular intruder or to certain stimuli emitted by it during the protracted interaction. In Experiment 2 subjects were given three sessions of 10 successive trials using either 1 intruder presented repeatedly, 2 intruders presented alternately, or 10 different intruders presented once each. No difference among conditions was found in this study either suggesting that subject's aggressive behavior is insensitive to whatever changes may occur in intruders' behavior or other stimulus characteristics when they have been treated with methotrimeprazine. The lack of differences among test conditions in both experiments is most likely due to the efficacy of the drug in “standardizing” intruder behavior. Experiment 2 also revealed an interesting difference in two measures of attack latency. The time elapsing between intruder presentation and attack, i.e., the standard measure of latency, decreased from the first to the fourth trail; it then increased steadily over the remaining trials. The cumulative time that the subject remained in contact with the intruder prior to attack, a measure more indicative of attention to the intruder, dropped to an asymptotic value by the second trial. This difference suggests that the satiation effect may be accounted for by subjects' increasing avoidance of the intruders over trails, perhaps as a way of regualting their level of aggressive arousal.