The social distraction of facial paralysis: Objective measurement of social attention using eye-tracking

Objectives: To measure the attentional distraction to the facial paralysis deformity using eye-tracking, and to distinguish between attention paid to the upper and lower facial divisions in patients with complete paralysis. We hypothesized that features affected by the paralysis deformity would distract the casual observer, leading to an altered pattern of facial attention as compared to normals.

Study design: Randomized controlled experiment.

Methods: Sixty casual observers viewed images of paralyzed faces (House-Brackmann [HB] IV-VI) and normal faces smiling and in repose. The SMI iView X RED (SensoMotoric, Inc., Boston, MA) eye-gaze tracker recorded eye movements of observers gazing on the faces. Fixation durations for predefined areas of interest were analyzed using three separate multivariate analyses.

Results: Casual observers gazing on both paralyzed and normal faces directed the majority of their attention to the central triangle (CT) region. Significant differences occurred in the distribution of attention among individual features in the CT and to individual sides of the face. Observers directed more attention to the mouth of paralyzed faces, smiling (analysis of variance [ANOVA] > F 0.0001) and in repose (ANOVA > F 0.0000). Attention was asymmetrically distributed between the two halves of paralyzed faces (paralyzed smiling minus normal smiling P > |z| 0.000).

Conclusions: Casual observers directed attention in a measurably different way when gazing on paralyzed faces as compared to normal faces, a finding exacerbated with smiling. These findings help explain society's perceptions of attractiveness and affect display that differ for paralyzed and normal faces and can be used to direct our reconstructive efforts.

Level of evidence: N/A.