Sex-dependent effect of threatening emotion on the perceived gaze direction

The integration of emotion and gaze direction is instrumental in understanding others’ intention and mental state. Previous studies have shown that threatening facial expressions have regulative effects on the perception of gaze direction. However, there was still a controversy about whether the sex of participants modulated the interaction between emotion and gaze direction. Here, we used a gaze direction judgment task to investigate whether the sex of participants modulated the emotional effect on perceiving the gaze direction. The cone of direct gaze (CoDG) was measured as a measurable index, which was put forward to acquire the scope of horizontal gaze directions within which a person perceived that others looked at himself/herself. A wider CoDG meant observers were more prone to regard others’ gaze as direct gaze. Results showed: 1) Perceiving the direction of gaze was mediated by emotion. Wider CoDGs for angry and fearful faces were found than those for neutral faces, and there did not exist such difference between angry and fearful faces; 2) Participants’ sex affected the perception of gaze direction, and the CoDG for men was significantly wider than that for women; 3) Participants’ sex modulated the role of emotion in gaze direction. With regard to the men, the CoDG for angry faces was significantly wider than that for neutral and fearful faces, and there existed a marginally significant difference in the CoDG between fearful and neutral faces. With regard to the women, the CoDG for neutral faces was significantly smaller than that for angry and fearful faces, and there did not exist the difference between fearful and angry faces. Therefore, our findings were partly in support of the shared signal hypothesis and indicated that the sex of participants could be a vital factor in modulating the interaction between gaze direction and facial expression.