Blocking facial mimicry during binocular rivalry modulates visual awareness of faces with a neutral expression

Thomas Quettier,Naotsugu Tsuchiya,Paola Sessa,Filippo Gambarota

doi:10.1038/s41598-021-89355-5

Thomas Quettier, Naotsugu Tsuchiya + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-89355-5

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Journal: Scientific Reports	Publication Date: May 11, 2021
Citations: 9	License type: open-access

Affiliation: University of Padua, Monash University

Abstract

Several previous studies have interfered with the observer’s facial mimicry during a variety of facial expression recognition tasks providing evidence in favor of the role of facial mimicry and sensorimotor activity in emotion processing. In this theoretical context, a particularly intriguing facet has been neglected, namely whether blocking facial mimicry modulates conscious perception of facial expressions of emotions. To address this issue, we used a binocular rivalry paradigm, in which two dissimilar stimuli presented to the two eyes alternatingly dominate conscious perception. On each trial, female participants (N = 32) were exposed to a rivalrous pair of a neutral and a happy expression of the same individual through anaglyph glasses in two conditions: in one, they could freely use their facial mimicry, in the other they had to keep a chopstick between their lips, constraining the mobility of the zygomatic muscle and producing ‘noise’ for sensorimotor simulation. We found that blocking facial mimicry affected the perceptual dominance in terms of cumulative time favoring neutral faces, but it did not change the time before the first dominance was established. Taken together, our results open a door to future investigation of the intersection between sensorimotor simulation models and conscious perception of emotional facial expressions.

Highlights

Several previous studies have interfered with the observer’s facial mimicry during a variety of facial expression recognition tasks providing evidence in favor of the role of facial mimicry and sensorimotor activity in emotion processing
Motor simulation models propose that the observer’s subthreshold motor simulation of the observed facial expression facilitates recognition and understanding of others’ congruent facial expression[23,24,25]. This theoretical view is supported by a substantial body of evidence. On one side it has been highlighted how brain regions supporting motor and somatosensory representations of facial expressions are involved in recognition of emotions in o thers[26], such that, for instance, lesions of these regions are associated with emotion recognition deficits[7,27] and, repetitive transcranial magnetic stimulation disrupting the right somatosensory[6, 28] and the right primary motor[29] cortices impairs some aspect of emotional face processing; on the other side there is evidence that muscular facial feedback incongruent with the observed expression causes a decrease in emotion recognition a ccuracy[26,30,31,32,33,34,35,36]
TAS-20 is one of the most commonly used measures of alexithymia traits, with a higher TAS-20 score indicating a higher inability to experience their own bodily emotions. Given that these tests were exploratory and since the study was not designed in terms of statistical power to directly answer this question on the relationship between alexithymic traits and binocular rivalry (BR) metrics for facial expressions, we report the results without strict corrections for multiple comparisons, so that future studies can look into the promising correlations in a planned confirmatory testing

Summary

Introduction

Several previous studies have interfered with the observer’s facial mimicry during a variety of facial expression recognition tasks providing evidence in favor of the role of facial mimicry and sensorimotor activity in emotion processing. On one side it has been highlighted how brain regions supporting motor and somatosensory representations of facial expressions are involved in recognition of emotions in o thers[26], such that, for instance, lesions of these regions are associated with emotion recognition deficits[7,27] and, repetitive transcranial magnetic stimulation disrupting the right somatosensory[6, 28] and the right primary motor[29] cortices impairs some aspect of emotional face processing; on the other side there is evidence that muscular facial feedback incongruent with the observed expression causes a decrease in emotion recognition a ccuracy[26,30,31,32,33,34,35,36], (and s ee[37,38,39,40]) The rationale behind this last series of studies is that, if facial mimicry—which can be measured by electromyography41,42—is a manifestation of sensorimotor simulation triggered by the observation of others’ facial expressions, an experimental manipulation aimed at interfering with it should interfere with the simulation process itself and affecting the processing of facial expressions. A recent sensorimotor simulation model has proposed that sensorimotor signals may feedback to visual areas modulating the visual processing of emotional faces from early stages[26,45]

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Results

Conclusion