Electrophysiological correlates of facial width-to-height ratio : An exploratory mass univariate study

Facial width-to-height ratio (FWHR), a facial metric, has been purported to predict threatening behaviors. Men with higher FWHR are perceived as more threatening and exhibit more threatening behaviors. In the current exploratory study, the aim was to elucidate the underlying electrophysiological correlates of FWHR. The study used computer-generated faces with varied emotional expressions, FWHR ratios, and vertical and horizontal facial features within the FWHR to examine how these features affect cortical activation measured using EEG and mass univariate analysis. Cortical activation elicited by high and low FWHR was expected to be different, as was activation for bottom and top eyebrows. Results demonstrated that angry faces and high FWHR faces elicited increased cortical activation associated with the late positive potential (LPP). These results suggest that high FWHR faces elicit activation associated with vigilance and arousal, similar to angry faces. Bottom-positioned eyebrows elicited higher cortical activation than top eyebrows. The eyebrow elicited cortical activation was also associated with the LPP. However, activation in response to variations in facial width was not significantly different. Surveyed subjective ratings for perceived threat were, for the most part, directly related to cortical activation. The results indicate that the increased perceived threat for high FWHR face may not be associated with FWHR directly, but rather bottom positioned eyebrows. These results provide indirect evidence for the anger resemblance view. However, research with more intricate and detailed face manipulations is needed to examine the underlying electrophysiological correlates of FWHR and its relation to perceived threat