Social Perception of Emotional Expression in Facial Synkinesis vs. Complete Facial Paralysis: A Narrative Review and Observer-Based Survey Data

INTRODUCTION: Facial paralysis is associated with social isolation, depression, anxiety, and impaired daily functioning. Affect display, defined as the outward facial expression of internal emotional states, is a key component of nonverbal communication and plays a central role in how individuals are perceived by others. Prior observer based research on social perception has largely treated facial paralysis as a single entity or has focused primarily on complete facial paralysis (CFP) despite meaningful clinical differences between CFP and facial synkinesis (FS). METHODS: We performed a narrative review of key studies examining affect display and social perception of patients with facial paralysis. We then conducted a prospective survey study of 557 adult casual observers who viewed 24 dynamic facial videos (8 CFP, 8 FS, 8 controls). After each video (repose to attempted smile), observers characterized the affect display of each face by selecting all applicable affects from the Derogatis Affects Balance Scale (DABS) plus a neutral affect. Mixed effects linear models were used to analyze the data. RESULTS: Most prior literature on social perception focuses on CFP and demonstrates that individuals with facial paralysis are perceived as less attractive, as having worse quality of life and as displaying more negative emotional states compared with controls. There remains limited literature specifically addressing FS. In the present study, observers (n = 557; mean age 36.5 years; 58.9% female) rated affect display after watching videos of patients with CFP, FS, and controls smiling. Relative to controls, FS faces were less likely to be labeled content, joyful, or vigorous and more likely to be labeled anxious and depressed. CFP faces showed more profound affective distortion: odds of being labeled joyful were ~98% lower (OR 0.02, 95% CI 0.01-0.04) and odds of being labeled depressed were >50 fold higher (OR 58.3, 95% CI 24.5-149.8) compared with controls. CONCLUSIONS: Both facial synkinesis and complete facial paralysis impair observer perception of positive affect display when attempting to smile and increase neutral or negative interpretations. This affect display penalty with attempted smiling is greater in CFP than in FS. These findings highlight distinct patterns of emotional misattribution across facial movement disorders and reinforce the importance of considering these conditions as separate entities in research and clinical care.