Abstract
Conditioned taste aversions (CTAs) occur when an animal forms an association between a taste stimulus and nausea, causing the animal to avoid that taste in the future. While CTAs are considered a basic form of “simple conditioning”, it is unknown how cognitive assessments influence such aversions. In this study, I use a CTA paradigm called backward blocking to examine rats’ abilities to reassess the safety of a taste cue indirectly, based on subsequent experience with another taste—a process called retrospective revaluation. Specifically, I test whether temporal separation of the taste cues during conditioning impacts backward blocking. Additionally, because explanations of retrospective revaluation are based in animals’ ability to create and modify causal connections between stimuli and outcomes, I test whether the addition of a novel taste stimulus during learning interferes with backward blocking.
My results show a complete lack of retrospective revaluation of CTA. No experimental group showed backward blocking of the target taste; instead, they showed representation-mediated conditioning. Rather than reassessing causal associations between stimuli, the animals mapped learning from one taste to another. The failure of any group to show clear evidence of retrospective revaluation reflects broader literature indicating that animals may be less likely to retrospectively revaluate CTAs, perhaps due to the significant evolutionary consequences of consuming illness-inducing foods. However, rats showed significantly different CTA strengths to NaCl and sucrose solutions despite receiving identical conditioning to those tastes, which may relate to their distinct values for survival and identifies an opportunity for future research.