The inhibitory effect of preexposed olfactory cues on intermale aggression in mice

To explore the effect of preexposure of olfactory cues on aggressive behavior, adult male mice, isolated for 14 days prior to the experiment, were preexposed for 10 days to one of 3 odors: (1) that of the opponent encountered in the test trial; (2) that of a strange mouse not subsequently encountered; and, (3) that of a neutral substance. The results show the greatest amount of aggression, as measured by latency to attack, accumulated attacking time, number of attacks and intensity of fighting, in the neutral preexposure group; an intermediate amount of aggression in the group preexposed to the irrelevant mouse odor; and the least amount of aggression in the group preexposed to the odor of the future-opponent mouse. Furthermore, preexposed animals in the third condition did not respond to attack by assuming the characteristic submissive posture. Results are discussed in terms of learned habituation to the pheromone which purportedly elicits aggression in the mouse.