Blocking facial mimicry affects recognition of facial and body expressions

Abstract

Facial mimicry is commonly defined as the tendency to imitate-at a sub-threshold level-facial expressions of other individuals. Numerous studies support a role of facial mimicry in recognizing others' emotions. However, the underlying functional mechanism is unclear. A prominent hypothesis considers facial mimicry as based on an action-perception loop, leading to the prediction that facial mimicry should be observed only when processing others' facial expressions. Nevertheless, previous studies have also detected facial mimicry during observation of emotional bodily expressions. An emergent alternative hypothesis is that facial mimicry overtly reflects the simulation of an "emotion", rather than the reproduction of a specific observed motor pattern. In the present study, we tested whether blocking mimicry ("Bite") on the lower face disrupted recognition of happy expressions conveyed by either facial or body expressions. In Experiment 1, we tested participants' ability to identify happy, fearful and neutral expressions in the Bite condition and in two control conditions. In Experiment 2, to ensure that such a manipulation selectively affects emotion recognition, we tested participants' ability to recognize emotional expressions, as well as the actors' gender, under the Bite condition and a control condition. Finally, we investigated the relationship between dispositional empathy and emotion recognition under the condition of blocked mimicry. Our findings demonstrated that blocking mimicry on the lower face hindered recognition of happy facial and body expressions, while the recognition of neutral and fearful expressions was not affected by the mimicry manipulation. The mimicry manipulation did not affect the gender discrimination task. Furthermore, the impairment of happy expression recognition correlated with empathic traits. These results support the role of facial mimicry in emotion recognition and suggest that facial mimicry reflects a global sensorimotor simulation of others' emotions rather than a muscle-specific reproduction of an observed motor expression.

Fig 1. Examples of face and body stimuli in Experiment 1.

Stimuli included happy, neutral and fearful expressions of the face or the body.

Fig 2. Examples of face and body stimuli in Experiment 2.

Stimuli included male and female actors showing happy and fearful expressions of the face or the body.

Fig 3. Trial example and facial manipulation.

Fig 4. Mean accuracy in Experiment 1.

When biting a pen, participants’ ability to recognize happy expressions was decreased relative to all the other conditions. Asterisks indicate significant comparisons. Error bars indicate s.e.m.

Fig 5. Mean accuracy in Experiment 2.

When biting a pen, participants’ ability to accurately identify happy expressions was decreased relative to all the other conditions. Asterisks indicate significant comparisons. Error bars indicate s.e.m.

Fig 6. Relation between changes in accuracy and individual differences in empathy disposition.

Scatter plot of the correlation between the behavioral index reflecting the costly influence of biting a pen on recognition of happy faces (accuracy in the Bite-happy condition minus mean accuracy across Lip-happy, Bite-fear and Lip-fear conditions) and individual scores on the IRI’s EC subscale (r = 0.34, p = 0.02). Grey and black dots represent participants in Experiment 1 and 2, respectively.