Further evidence that Norway rats do not socially transmit learned aversions to toxic baits

Abstract

Three experiments were undertaken to examine the effects of interactions with demonstrator rats made ill by injection of lithium chloride (Lifll) on the later food choices of their observers. We found that (1) observer rats that had been taught an aversion to an unfamiliar diet exhibited a substantial reduction of that aversion after interacting with poisoned demonstrators that had eaten the diet to which the observers had learned an aversion, (2) exposure of an observer rat to poisoned demonstrator rats that had eaten a diet interfered with later acquisition by the observer of an aversion to the diet that the poisoned demonstrators had eaten, and (3) after interacting with poisoned demonstrators that had eaten one of two diets, observers that ate both diets and were then made ill formed an aversion to whichever diet their respective, poisoned demonstrators had not eaten. The present experiments, like previous studies both in our laboratory and elsewhere, failed to provide any evidence that naive observer rats will learn to avoid a food as a result of interacting with demonstrator rats that had eaten the food and exhibit symptoms of toxicosis. To the contrary, observer rats in the present experiments exhibited an enhanced preference for foods eaten by sick demonstrators.

Enhancement of food aversion by exposure to a poisoned conspecific in Norway rats (Rattus norvegicus)

“…If subjects increase their aversion to the food eaten by a poisoned conspecific on the subsequent choice test, the results will support Hishimura's (1998) findings. On the other hand, if subjects decrease their aversion, the results will support the findings of Galef et al (1990).…”

“…Some studies have shown that animals utilize information provided by their conspecifics in relation to food aversions (e.g., Coombes, Revusky, & Lett, 1980;Galef, McQuoid, & Whiskin, 1990;Galef, Wigmore, & Kennett, 1983;Gemberling, 1984;Hishimura, 1998;Kuan & Colwill, 1997). One way to analyze this issue is to present a poisoned conspecific to subjects after the latter have received foodaversion conditioning.…”

On the Psychology of the Recognition Heuristic: Retrieval Primacy as a Key Determinant of Its Use

“…In these evolutionarily important domains, recognition is typically observed to be used in a noncompensatory way (e.g., Galef, McQuoid, & Whiskin, 1990). In light of its evolutionary history, Goldstein and Gigerenzer (2002, p. 77) referred to recognition as a "primordial psychological mechanism" and proposed that the capacity for recognition is being co-opted for drawing probabilistic inferences in the here and now.…”

Social influence on avoidance of dangerous stimuli by rats

“…Surprisingly, although such social facilitation of the acquisition of appetitive responses has been demonstrated repeatedly in Norway rats, and socially learned avoidance of potentially dangerous objects has been demonstrated many times in vertebrate species other than rats (Curio, 1988;Mason, 1988;Mineka & Cook, 1988), rats have not been shown to learn avoidances socially (Galef, McQuoid, & Whiskin, 1990;Galef, Wigmore, & Kennett, 1983).…”