Preference for and discrimination of videos of conspecific social behavior in mice.

We showed mice videos of three conspecific social behaviors, namely sniffing, copulation, and fighting, in pairwise combinations using iPods and evaluated preference as determined by time spent in front of each iPod. Mice preferred the copulation video to the sniffing video, the fighting video to the sniffing video, and the fighting video to the copulation video. In Experiment 1a, we used a single video clip for each social behavior but used multiple video clips for each social behavior in Experiment 2a. Next, we trained mice to discriminate between the fighting and copulation videos using a conditioned-place-preference-like task in which one video was associated with injection of morphine and the other was not. For half of the subjects, the fighting video was associated with morphine injection, and for the other half, the copulation video was associated with morphine injection. After conditioning, the mice stayed longer in the compartment with the morphine-associated video. When tested with still images obtained from the videos, mice stayed longer in the compartment with still images from the video associated with morphine injection (Experiment 1b). When we trained mice with multiple exemplars, the subjects showed generalization of preference for new video clips never shown during conditioning (Experiment 2b). These results demonstrate that mice had a preference among videos of particular behavior patterns and that they could discriminate these videos as visual category. Although relationship between real social behaviors and their videos is still open question, the preference tests suggest that the mice perceived the videos as meaningful stimuli.