Self-report measures rely on cognitive and rational processes and may not, therefore, be the most suitable tools to investigate implicit or unconscious factors within a sensory experience. The responses from the autonomic nervous system (ANS), which are not susceptible to bias due to their involuntary nature, may provide a better insight. Expectations are important for the consumer-product interaction and should be considered. However, research using ANS responses has not focused thoroughly on expectations. Our aim was to investigate the mechanisms underlying ANS responses by evaluating the reactions to different images when expectations about a product are created (before tasting the product) and when they are confirmed and disconfirmed (after tasting the product). In a first study, seventy-five participants tasted four drinks (three identical soy-based drinks and one rice-based drink) and were told that they would be shown their main ingredient either before or after tasting. For the three identical drinks, the images shown were: worms, chocolate, and soy. Heart rate and skin conductance were measured during the procedure. The results showed that ANS responses followed similar patterns when images were presented before or after tasting. Heart rate decreased for all images, with the largest decrease found for chocolate and worms. Skin conductance increased, with the largest increase found for worms. To test whether the effects were solely caused by image perception, a second study was done in which forty participants only saw the images. The responses obtained were smaller and did not completely match those of the first study. In conclusion, it could be said that the ANS responses of the first study were a result of the sensory processing and defense mechanisms happening during the creation and (dis)confirmation of expectations. The second study confirmed that visual perception alone could not account for these effects and that it led to smaller changes. Hence, it seems that the context of use influences the patterns and magnitude of ANS responses to food cues.

Disconfirmations between consumers’ expectations and a product’s actual properties can lead to different responses in consumers. Most researchers study these responses focusing on the final judgement of the product. However, looking at consumers’ physiological responses like those of the autonomic nervous system (ANS) could help complement what is known about consumer reactions and final response to disconfirmed expectations. This study evaluated how ANS responses change when tasting juice samples that were as expected, that differed slightly, or that differed greatly from manipulated expectations and whether these responses vary from those obtained when there is no manipulation of expectations. Eighty-six participants tasted fruit and vegetable juices in two separate sessions. They were divided in two conditions. In Condition A, expectations were manipulated by showing participants the image of an ingredient and then providing them with a juice whose flavour was as expected, differed slightly, or differed greatly from that of the image. In Condition B, each juice was first tasted without explicit information shown beforehand and the image of the ingredient was shown afterwards. The images were the same as in Condition A. Heart rate and skin conductance were measured. To confirm that participants perceived confirmations and large and small disconfirmations when tasting the juices, they rated the samples in different sensory properties before and after tasting them. Results from most of the sensory ratings, except sourness and taste intensity, showed that participants perceived the designed confirmation and disconfirmation of expectations accordingly. Regarding ANS responses, heart rate had a larger increase during the second session than during the first. Skin conductance responses increased in Condition A but decreased in Condition B. In conclusion, our design managed to create confirmations and varying levels of disconfirmations. ANS responses did not capture them but seemed to capture factors like attention and the orientation response.