Nonsocially housed rats (Ratus norvegicus) seek social interactions and social novelty more than socially housed counterparts.

Sociability is the act or quality of social interaction and can be quantified by determining the number and duration of interactions with conspecifics. The purpose of this study was to examine the extent to which sustained social contact, as achieved by constant social living conditions, influenced social behavior. Beginning in juvenility, 19 male Long-Evans rats were housed in enriched environments, with half living socially in a large group and half living individually. After several months in these housing conditions, rats were tested on a sociality test and a social novelty preference test. Nonsocially housed rats exhibited more social behavior than socially housed rats. In the sociality test, nonsocially housed rats engaged with an unfamiliar rat more than socially housed rats. Similarly, in the social novelty test, nonsocially housed rats visited a novel stranger more than the now-familiar rat (from the sociality test) as compared with the socially housed rats. It is unlikely that general anxiety factors can account for between-groups social effects, as there were no group differences in behavior on the elevated zero maze and open field test. Furthermore, socially and nonsocially housed rats were matched in spontaneous object exploration and novelty preference in a novel object recognition test, eliminating the possibility that general exploratory behavior or novelty preference accounted for group differences in the sociability tasks. These results suggest that lack of social interaction in nonsocially housed rats may be more powerful for social motivation than the consistent opportunity for social contact afforded by social living conditions. (PsycINFO Database Record