Flavor-toxicosis associations: tests of three hypotheses of long delay learning.

Rats were prepared with gastric cannulas and esophageal fistulas to assess the contribution of taste and smell, postingestinal stimuli, and the combination of the two in forming flavor-toxicosis associations. Groups were either given sugar water to drink, a stomach intubation of sugar water, both sugar water to drink and a stomach intubation of sugar water, or not given sugar water. The experimental and pseudo-conditioning control animals were given a LiCl injection and the control animals were given a NaCl injection one hour later. They were tested for drinking of sugar water the next day. It was found that taste and smell are the primary stimuli for forming food aversions. Furthermore, postingestional stimuli are not sufficient to produce this type of learning.