GREGARIOUSNESS AND FEAR IN LABORATORY RATS

Forty-eight rats were observed both alone and in pairs in a circular open field for five days. When tested together, rats were highly gregarious, staying much closer together than expected by chance. They also showed less defecation and freezing when to-gether than alone. Both gregariousness and fear-reduction increased over days of testing. To resolve the apparent conflict with previous results showing little gregariousness in rats, a second experiment compared the attractive power of an empty cage, a caged rat, and a freely moving partner. Again, rats tested together showed high and increasing gregariousness. The caged rat, however, was not significantly more attractive than an empty cage. © 1969.