A comparison of learned aversions to gustatory and exteroceptive cues in rats

The experiment provides a direct comparison of the ability of subjects (rats) to associate gustatory and exteroceptive stimuli with illness. Previous experiments which have made similar comparisons between gustatory and exteroceptive cues have suffered from certain methodological problems involving stimulus control and compounding. The present experiment utilized a between-subjects design wherein half of the subjects had an auditory cue associated with poisoning and half had a taste cue. In both cases, the other cue was present, but was not predictive of poisoning, The auditory cue, like the taste cue, occurred only during drinking. This comparison was made in both an immediate and a delayed poisoning situation. The experiment found that while subjects were able to quickly associate a taste cue with illness, they were unable to form a similar association between poisoning and the exteroceptive stimulus. Results also showed that subjects will fail to acquire a taste aversion to a novel and salient gustatory cue when that cue is followed by illness only 50% of the time. This latter effect was more pronounced in the delayed poisoning situation.