Neophobia: generality and function

Abstract

The hypothesis that neophobia varies directly with the flavor of toxic substances in the natural habitat of a species, and possibly also with the flavors of necessary nutrients in the natural habitat is examined in eight experiments using rats, guinea pigs, and gerbils. Neophobia was found to be an inverted U-shaped function of concentration. After examining diverse concentrations when neophobia was not immediately evident, relative to sweet, bitter, or salty flavors, rats were determined to possess little neophobia to sour flavors, at least citric acid and ascorbic acid; guinea pigs exhibited strong neophobia to sour, sweet, and salty solutions and weak neophobia to a bitter solution; and gerbils showed no neophobia to any flavor. Although within-species neophobias apparently depend on flavor concentration, the observed between-species differences in neophobia to a common concentration appear incompatible with expectations based upon considerations of either ecological dangers or nutritional needs. Moreover, all three species acquired with equal ease conditioned taste aversions to the same flavor concentrations that had yielded decidedly different degrees of neophobia. Thus, in neither rats nor gerbils did neophobia to different flavors reflect differences in propensity to form conditioned taste aversions. Neophobia appears to be a relatively weak phenomenon seen only in some species and then not to all substances, whereas conditioned taste aversion is seen to be a robust phenomenon that transcends species and can be formed to any novel flavor.