Reversal of innate aversions: Attempts to induce a preference for chili peppers in rats.

Abstract

Although humans frequently develop preferences for innately unpalatable bitter or irritant substances, such preferences are extremely rare in animals. An attempt was made to understand the nature of this difference by systematic experiments with laboratory rats, with chili pepper as the unpalatable substance. In parallel with major aspects of the human experience with chili pepper, rats were exposed to it as a flavoring in all their food for periods up to 11 mo from birth, without significant preference enhancement. Gradual introduction of chili into the diet also had no effect, nor did a series of poisoning and safety experiences designed to teach the rats that only chili-flavored foods were safe to eat. A sequence of seven pairings of chili-flavored diet with prompt recovery from thiamine deficiency did significantly attenuate the innate aversion and may have induced a chili preference in at least one case. Extensive experience with chili did not reliably make rats much less sensitive to its oral effects. The only reliable way to eliminate chili aversion in rats is to destroy their chemical irritant sense, which was accomplished in one group of rats. It is concluded that in contrast to humans, it is extremely difficult to reverse innate aversions in rats.

Maternal ingestion of ortho-aminoacetophenone during gestation affects intake by offspring

“…Again, there are data consistent with this notion. Rats develop temporary preferences for chili peppers if previous experiences with peppers have been paired with recovery from thiamine deficiency (27). Likewise, rats develop a preference for the flavor of morphine once it is associated with its psychogenic consequences (35).…”

The cultural niche: Why social learning is essential for human adaptation

“…Nonhuman primates and human infants find peppers aversive because capsaicin stimulates pain receptors in the mouth. Efforts to inculcate a taste for chilies in rats using reinforcement procedures have failed (55). However, human food preferences are heavily influenced by the preferences of those around us (56), so we overcome our innate aversion and actually learn to enjoy chilies.…”

Neural Plasticity in the Gustatory System

“…[6][7][8][9] Indeed, a conclusion from these initial studies was that the gustatory system is remarkably resistant to environmental manipulations. 9 The most consistent manipulation that was successful in altering peripheral taste responses, however, was dietary sodium depletion.…”