Social influences on the identification of toxic foods by Norway rats

In the present experiments, a naive “observer” rat first interacted with a “demonstrator” rat previously fed a diet unfamiliar to the observer. The observer then sampled two unfamiliar diets, one of which was the diet its demonstrator had eaten. The observer was then injected with LiCl and, following recovery from toxicosis, was offered a choice between the two diets it sampled prior to toxicosis induction. It was found that: (1) each observer rat formed an aversion to whichever diet its demonstrator had not eaten, (2) effects of demonstrators on aversion learning by observers were present even if there was a 7- or 8-day delay between interaction of a demonstrator and observer and diet sampling by the observer, and (3) observers interacting with 3 demonstrators, each fed a different diet, subsequently exhibited a reduced tendency to form an aversion to each of the diets eaten by their demonstrators. Taken together, the results indicate that information acquired from conspecifics as to the diets they have eaten can play an important role in determining the foods to which otherwise naive rats will learn aversions.