Probing the connection between facial mimicry and visual processing of emotions

BACKGROUND AND AIM: Simulation models of facial expressions suggest that posterior visual areas and brain areas underpinning sensorimotor simulations might interact to improve facial expression processing. According to these models, facial mimicry--a manifestation of sensorimotor simulation--may contribute to the visual processing of facial expressions by influencing its early stages. To date, there is no evidence yet providing direct evidence of this potential link. We present two studies aimed to fill this gap, assessing whether and how early sensorimotor simulation influences the earlier and the later stages of face processing, investigating its relationship with personality traits. Methods: In Exp. 1, we monitored the P1 and the N170 ERP components of the event-related potentials (ERP) in participants performing a fine discrimination task of facial expressions and animals--as a control condition. In half of the experiment, participants could freely use their facial mimicry whereas in the other half they had their facial mimicry blocked by a gel. In Exp. 2, we monitored the ERP marker of visual working memory (VWM) representations, i.e. the sustained posterior contralateral negativity (SPCN), while participants performed a change detection task including to-be-memorized faces with different intensities of anger. As for the Exp. 1, in half of the experiment, participants performed the task with their mimicry blocked. RESULTS: Our Exp. 1's results revealed that individuals with lower alexithymic traits showed a larger modulation of the P1 amplitude as a function of the mimicry manipulation for facial expressions (compared to animals), while we did not observe any modulations of the N170. In Exp. 2, SPCN amplitude was reduced for faces in the blocked mimicry condition when compared to the free mimicry condition. This modulation interacted with the empathy levels of participants such that only participants with medium-high empathy scores showed such reduction of the SPCN amplitude when their mimicry was blocked (Figure 2). CONCLUSIONS: Taken together, these findings provide evidence that facial mimicry influences both early and high-level visual processing of facial expressions depending on individual differences. ACKNOWLEDGEMENTS AND FUNDING: We would like to thank the University of Padova at the Department of Developmental Psychology and Socialization for having given us the possibility to run these two experiments in their laboratories and Dr Adrienne Wood for kindly providing us with the stimuli used in the present study (see Wood et al., 2015). This research received no specific grant from any funding agency.