Abstract
Moebius Syndrome (MoS), a rare congenital neurological disorder, is characterized by total or partial paralysis of the VIth and VIIth cranial nerves resulting in paralysis of the face, and a lack of skeletal muscle feedback. The facial feedback hypothesis, a prominent concept in face perception, asserts that feedback from the skeletal muscle of the face alters the experience of emotion (Buck, 1980; Soussignan, 2001; Strack, Martin, & Stepper, 1988). Thus, it is possible that patients with MoS may have trouble identifying or processing emotion. Several studies have examined the ability of individuals with MoS to recognize familiar and unfamiliar faces (Calder et al., 2000; Bate et al., 2013), to experience and express emotion (Cole, 2010), and to recognize and label facial expressions (Giannini et al, 1984; Calder et al, 2000; Bogart & Matsumoto, 2010; Bate et. al, 2013). However, results from these studies have been mixed and it is thus unclear whether MoS may lead to deficits in emotion processing. One reason for the conflicting results could be that most of the studies used an emotion-labeling task, which may not have been sensitive to subtle deficits in emotion processing. Thus, in our study we used morphs of neutral to happy or fearful faces, and an emotion detection task to measure emotion perceptual thresholds for each participant. Subjects viewed fearful and happy images containing different amounts of emotion and indicated with a button press whether the image did or did not contain emotion. A one-up, three-down staircasing procedure was used to determine each participant's threshold for 79% accuracy. Results showed that individuals with MoS, as compared to healthy controls, showed a deficit in detecting emotion. These results indicate that the paralysis of and lack of feedback from the facial muscles may impair emotion perception in individuals with MoS.
Meeting abstract presented at VSS 2016