Behavioral disassociation of perceived sweet taste intensity and hedonically positive palatability
The intensity of sucrose (its perceived concentration) and the palatability (its positive hedonic valence associated with ingestion) are two taste attributes that increase its attractiveness and overconsumption. Although both sensory attributes covary, in that increases in sucrose concentration leads to similar increases in its palatability, this covariation does not imply that they are part of the same process or whether they represent separate processes. Both these possibilities are considered in the literature. For this reason, we tested whether sucrose’s perceived intensity could be separated from its hedonically positive palatability. To address this issue, rats were trained in a sucrose intensity task to report the perceived intensity of a range of sucrose concentrations before and after its palatability was changed using a conditioned taste aversion (CTA) protocol. We found that the subjects’ performance remained essentially unchanged, even though its palatability was changed from hedonically positive to negative. Overall, these data demonstrate that sucrose’s perceived intensity and its positive palatability can be dissociated, meaning that changes of one taste attribute render the other mostly unaffected. Thus, the intensity attribute is sufficient to inform the perceptual judgments of sucrose’s concentrations.
SIGNIFICANCE STATEMENT Subjects trained to classify sucrose concentrations could guide their decisions based on their perceived intensity and/or palatability. Despite the fact that both taste attributes covary with changes in sucrose concentration, we found that it was possible to change its hedonically positive palatability attribute without affecting the sensitivity to identify sucrose’s perceived intensity. That is, the subjects perceptual judgments of sucrose concentrations were based on the information provided by the intensity attribute showing, for the first time, that the hedonically positive aspect of sucrose’s palatability and its perceived intensity could be completely dissociated.