Heart rate and skin conductance responses to taste, taste novelty, and the (dis)confirmation of expectations

It is unclear whether the responses of the autonomic nervous system (ANS) can measure how people respond to food. Results focused on emotional responses are contradictory; therefore, the focus has shifted to other components of emotion, such as appraisals. The aim of this study was, therefore, to evaluate the differences in ANS responses related to appraisals; particularly taste novelty, valence, and the disconfirmation of expectations.A hundred and fifty-five participants joined this study. They tasted samples of different valence (sweet and bitter) twice: the first time without knowing the taste and the second while being informed of the taste. After this first block, participants tasted two additional samples: one that confirmed expectations and one that disconfirmed them. Heart rate and skin conductance were measured. Results show that the second experience with a taste led to cardiac deceleration. Heart rate changes were only related to valence when participants' expectations were (dis)confirmed. Heart rate decreased for those tastes that disconfirmed expectations and increased for those that confirmed them and the sweet sample had larger increases in heart rate than the bitter. Skin conductance changed in regards to novelty and valence but not to the disconfirmation of expectations. It increased for the bitter sample, decreased for the sweet, and was always higher during the first experience than during the second. In conclusion, the results suggest that cardiac responses are more sensitive to novelty and the disconfirmation of expectations while skin conductance responses capture novelty and valence