Deficits of visual working memory representations of emotional facial expressions in patients with congenital facial palsy

Recent models of sensorimotor simulation postulate that simulation aids ‘refining’ visual representations of others’ emotional facial expressions through an iterative communication with the visual system. In order to test this aspect of sensorimotor simulation models, in the present investigation we recruited a sample of patients with Moebius syndrome (MS), characterized by congenital facial paralysis, and a control group of healthy participants. MS patients constitute a particularly interesting test as their congenital impossibility of producing facial movements and expressing emotions through the face should translate into a deficit of facial expressions processing. Here, MS and healthy participants underwent a task aimed at measuring the precision with which representations of facial expressions of emotions are maintained in visual working memory (VWM) by implementing a delayed estimation task. In each trial, participants saw a face with a certain intensity of facial expression (i.e., of happiness, disgust or anger) and, after a short time interval of about 1 sec, they had to select the to-be-memorized image inside a circular array in which facial expressions of increasing intensity were presented in an orderly manner. The results indicated that MS participants built lower quality representations of the intensity of emotional expressions when compared to healthy participants. These findings support the role of sensorimotor simulation in improving the quality of emotional representations of facial expressions during early stages of processing.