Which features depend on which faces?

Schwartz et al. (ARVO '98) found that observers asked to identify facial expressions use only the mouth area of the face. Paul Ekman objected that her faces were not expressing emotions, and predicted that for emotive faces, observers would use both the mouth AND the eyes. To test his prediction, we measured thresholds for identifying emotions in the presence of a noise curtain that was swept horizontally and vertically across the faces. We find that observers identify emotions by using either the eyes OR the mouth.