Signaling with the Eyebrows – Commentary on Huron, Dahl, and Johnson

Huron, Dahl, and Johnson, in their paper "Facial Expression and Vocal Pitch Height: Evidence of an Intermodal Association", demonstrated a positive correlation between the pitch of a sung note and the vertical position of the singer's eyebrows. Moreover, other subjects viewing photographs of the faces of the singers, with the lower part of the face and neck of the singers blocked out, could accurately judge whether a high note or low note had been sung. The authors offer a number of hypothetical explanations for their findings. I propose a speculative, ethologically-based, explanation for these correlations: namely, how both pitch of voice and eyebrow position would be correlated in this way to convey to the viewer the degree of potential threat - or lack of threat - posed by the signaler. Submitted 2009 October 1; accepted 2009 October 12.