Fear and affiliation in domesticated male rats.

Abstract

Male rats actively seek the opportunity to interact with other male rats. Three experiments examined the hypothesis that the presence of conspecifics can reduce the behavioral signs of fear in rats and that this capacity provides part of the attraction to conspecifics. The immobility response of male rats was measured following exposure to a stressful noise. The animals that were observed in groups exhibited shorter durations of immobility than the animals that were observed alone. The group effect was sufficiently powerful to nullify different housing conditions and different degrees of familiarity among the males. The 2nd experiment compared social and nonsocial stimuli and found that only the former stimuli effectively reduced the immobility response. Stressed rats were more likely to choose to interact with a conspecific in a T-maze than were nonstressed rats. Rearing conditions made little difference; both the individually and group housed males were highly attracted to a conspecific.