4. Discussion
Our proof-of-concept study demonstrates that a cognitive intervention, under certain circumstances, may revert conditioned food aversion, and restore the reward value of an originally pleasant meal in healthy women.The probe meal in the present study, a tasty hummus, induced the pleasant response characteristic of a comfort meal. Aversive conditioning was achieved by administration of the same hummus containing a hidden fat overload that did not affect its organoleptic characteristics, specifically the palatability, but induced an aversive postprandial response. After this experience, subjects became conditioned and reacted to the original comfort meal mimicking their response to the offending meal. In the test group, the cognitive intervention reverted conditioning through an unlearning process and restored the original response to the comfort meal. By contrast, in the control group, the response to the originally comfort meal, particularly meal wanting and liking, further deteriorated through re-exposure, suggesting that some degree of aversive reinforcement took place.Taste aversion and aversive conditioning of the postprandial experience, both in nonhuman animals and in humans, as in the present study, can be acquired after a single conditioning trial [Disclosing the prior conditioning paradigm, and realization of the true situation, resulted in unlearning and reversion of conditioning. We have previously shown that, using a cognitive–sensory intervention, healthy subjects learn to heighten their hedonic response to a comfort meal [Based on previous experience [Our conditioning paradigm involved a colour clue (non-coloured meals before conditioning on day 1 and after the intervention on day 4, in contrast to colour-labelling of the offending meal on day 2 and postconditioning meal on day 3), but we cannot ascertain whether the colour clue influenced the effect of the intervention. However, in the control group, the response to the regular-fat meal on the fourth day induced an aversive response even without the colour label, indicating that conditioning was not colour-specific. It has been previously shown that other forms of conditioning affect related stimuli by a phenomenon of generalization [An important contribution of our study is the focus on the postprandial experience over taste. Taste aversion in nonhuman animals function as a protective mechanism to prevent ingestion of potentially noxious foods [