Skin conductance responses to oral stimuli: The role of taste quality and intensity, and personality traits

Measuring emotional responses to tastes and foods, using both self-reports and also implicit and physiological measurements is gaining attention. Among physiological measurements, skin conductance response (SCR) is one the most commonly used indicators of emotional activation but it has been rarely applied to taste and other oral stimuli and its interpretation is not yet clear. Furthermore, the effect of individual differences in SCR to tastes has been rarely taken into account. To address these issues, SCR to bitter, astringent, and sweet samples presented both at weak/moderate and moderate/strong intensity was recorded while eighty Italians, selected based on PROP (6-n-propylthiouracil) status (only Medium-Tasters), performed an implicit affective test. Samples were presented blind in aqueous solutions monadically in triplicate. Subjects (Ss) were asked to taste a sample, then a neutral face was briefly presented on a screen, and Ss were asked to indicate if they trusted the face (yes/no) and how much (on a 9-point Scale). Data on Ss’ psychological traits (anxiety, sensation seeking, food neophobia, emotional stability) was also collected. Two clusters were identified based individual SCR. These clusters differed in their SCR mainly to strong bitterness, and partially to astringency, while they did not differ for their response to the sweet samples. The High bitter responders were more anxious and neurotic than Low bitter responders. For this cluster higher intensities induced higher SCR, but this was not found in the Low bitter responders cluster that tended to have higher SCR to the least intense samples. No differences in the implicit affective responses to samples were found between clusters. These results indicate that SCR to tastes reflect mainly different sources of arousal, such as novelty/surprisingness, quality and intensity of the stimuli, and this may change at an individual level. This suggests that measurement of SC can contribute to a better understanding of individual differences in taste and oral experience and could provide a link between taste responsiveness and sympathetic nervous system activity.