In general, naïve individuals appear more likely to learn from interaction with familiar rather than unfamiliar members of their species. Kaveliers and colleagues (2005) reported that naïve laboratory-bred deer mice showed greater social learning of defensive responses to biting flies after observing responses of familiar members than after observing responses of unfamiliar members. Earlier, Valsecchi and colleagues (1996) reported striking differences in social learning of food preferences among Mongolian gerbils, depending on whether they were exposed to familiar or unfamiliar demonstrators. At the time, this was unexpected because Gaief and colleagues (1984) had previously reported no familiarity effect in Norway rats on social learning of food preferences. However, Gaief et al (1998) subsequently uncovered a significant familiarity effect that was evident when demonstrators are some hours before interacting with observers but absent when demonstrators are immediately before interacting.