Pupil dilation and self-reported emotional response to IAPS pictures: the role of emotional regulation and trait mindfulness

Mindfulness has been associated with reduced emotional reactivity, with meditators showing an increased pupillary contraction and a weaker dilation to negative stimuli with respect to non-meditators. However, the role of individual differences in determining such different pupillary responses has not been assessed in this regard. Thus, we designed a pupillometry study with affective picture viewing in which we investigated for the first time whether self-reported measures of mindfulness and emotional regulation related to the pupil response. We collected pupil dilation data from 29 participants viewing a set of IAPS images with positive, neutral, and negative valence, presented in randomized order. For each image, we also collected subjective emotional experiences on three dimensions: valence, arousal, and dominance. Moreover, participants completed a battery of questionnaires assessing trait mindfulness and emotional regulation abilities. We found significant effects of image valence on both subjective ratings and pupillary response to the three different categories. We also found that emotional regulation affected the pupil minimum and maximum dilation in response to emotional stimuli, pleasant or unpleasant, while mindfulness reduce the time for recover pupil dilation after the first contraction in response to the stimulus onset. Overall, these results suggest that mindfulness had physiological effects on autonomic response and emotional regulation.