“…While it is less clear whether the zygomaticus major (smiling) muscle is sensitive to bipolar valence (Larson et al, 2003) it is sensitive to positive affect with increased activation for positive stimuli (Larsen et al, 2003;Williams, Leong, Collier, & Zaki, 2019;Winkielman & Cacioppo, 2001). For instance, a recent study provided evidence that zygomaticus activity during presentation of positive (but not negative) movie scenes was highly correlated with subjective ratings of participants, but also closely tracked dynamic changes of positive affect in the movies over time (Golland, Hakim, Aloni, Schaefer, & Levit-Binnun, 2018). Interestingly, when performing a simple response-interference task (and without any affective stimuli presented), Lindström and colleagues showed stronger EMG over the corrugator supercilii muscle within 200 ms following an error relative to a correct trial (Lindström, Mattsson-Mårn, Golkar, & Olsson, 2013).…”