An electromyographic investigation of the impact of task relevance on facial mimicry

Abstract

When viewing a face expressing emotion, the viewer's face mimics the same emotion. It is unknown whether such facial mimicry takes place when the viewed emotion is a task irrelevant property of the face. The present experiment addressed this question by asking participants to judge either the emotional expression or the colour of a series of happy and angry faces that were either blue or yellow. Electromyographical recordings showed that when emotion was ignored, there was a tendency for facial muscle activity to be suppressed. Nonetheless, participants’ facial expressions mimicked target expressions, with the zygomaticus cheek muscle being more active when viewing a smiling face and the corrugator brow muscle more active when viewing an angry face. These data support the automatic encoding of irrelevant emotional information, as well as suppression of emotional information by selective attention.

Keywords:

• Simulation
• Mimicry
• Attention
• Emotion
• Electromyography

Acknowledgements

This research was supported by Economic and Social Research Council grant RES-000-23-0429 awarded to SPT and AEH. Development of the MacBrain Face Stimulus Set was overseen by Nim Tottenham and supported by the John D. and Catherine T. MacArthur Foundation Research Network on Early Experience and Brain Development.

Notes

¹Please contact Nim Tottenham (at [email protected]) for more information concerning the MacBrain stimulus set.

²Autism quotient data did not influence facial mimicry and these data are not discussed further.

³During the fixation period for the non-standardised rectified integrated data, there was a main effect of muscle site (p<.001), with higher activity at the corrugator site than the zygomaticus site; although there was no difference in muscle activity between tasks (F<1).

⁴While this effect is statistically marginal, it is an a priori predicted directional effect and can be considered significant.