Facial palsy reveals the sensorimotor contribution to facial-emotion recognition

Abstract

Significance How do we recognize emotions from other people’s faces? A long-standing debate opposes two answers: that we match faces to learned visual patterns, or that we covertly draw on our own facial movements. Facial palsy provides a natural experiment. It removes facial movement without artificial interference, and contrasting people paralyzed from birth (Moebius syndrome) with those paralyzed later in life isolates the role of early motor experience. Grading residual movement, we found that it predicted recognition of ambiguous expressions, but not of clear ones—except in those affected from birth, where it predicted recognition even of clear expressions. The result turns a long-standing either-or debate into a testable account of when and why visual and sensorimotor information each contribute.