What faces reveal: impaired affect display in facial paralysis

Objectives/hypothesis: To evaluate affect display in patients with facial paralysis as compared with normal subjects. We hypothesized that patients with facial paralysis would have impaired affect display and be perceived as displaying a negative affect as compared with normal subjects.

Study design: Randomized controlled experiment.

Methods: Forty naive observers viewed pictures of patients with facial paralysis and normal faces. Observers classified the affect display of the patients and normal subjects by using a survey containing choices regarding primary emotions and personal attributes.

Results: An exploratory latent class analysis was performed on the survey results, and the faces were categorized into three types: positive, negative, and neutral. The probability of interpreting normal smiling faces as positive was 98%; the probability of interpreting those in repose as neutral or positive was 60%. The faces with facial paralysis were much more likely to be regarded as negative or neutral. The probability for classification into the negative class was 73% for the paralyzed faces in repose and 69% for the paralyzed smiling faces. In the latent class regression, smiling normal faces were six times more likely to be classified as positive, and smiling paralyzed faces were three times less likely to be in that class.

Conclusions: Patients with facial paralysis were classified as having a negative affect display the vast majority of the time. Antithetically, normal faces in repose were classified as neutral the majority of the time; they were classified as positive the majority of the time when smiling. These novel results demonstrate the impact of the facial paralysis defect on perception by observers. Laryngoscope, 2011.