Sensitivity to basic emotional expressions and the emotion perception space in the absence of facial mimicry: The case of individuals with congenital facial palsy

According to sensorimotor simulation models, recognition of another person's emotion is achieved by recreating the motor production of the perceived facial expression in oneself. Therefore, congenital difficulties in the production of facial expressions may affect emotion processing. The present study assessed a sample (N = 11) of Moebius syndrome (MBS) patients and a matched control group (N = 33), using a highly sensitive emotion recognition task. Leveraging the uniqueness of MBS, which is characterized by congenital facial paralysis, the role of facial mimicry and sensorimotor simulation in creating precise embodied concepts of emotion categories was investigated. Particularly, the research focused on how MBS patients (both as a group and individually, compared to controls) perceived the intensity of primary emotions and how well they discriminated between these and secondary (i.e., blended) emotions. The results showed that MBS patients registered significantly lower intensities for sadness, fear, anger, and disgust. Furthermore, these emotions appeared closely clustered-and therefore confused with anger and surprise-in the multidimensional scaling map, which was used to qualitatively analyze the emotion perception space. Further analysis of each MBS participant showed a stronger tendency in most patients to perceive primary emotions as less intense, relative to controls. Thus, the findings provide evidence for a residual deficit in emotion processing in adults with MBS.