Abstract
Bruce and Young's (1986) model of face recognition proposed that facial identity and emotional expression are processed independently. Yet, it has been argued that certain processes such as the perception of configural information are an important part of both face recognition and expression perception that can be marred by contrast negation and inversion (Calder & Jansen, 2005; Hole, George, & Dunsmore, 1999). To further investigate the proposed dichotomy between expression perception and the encoding of other facial attributes, we systematically measured threshold sensitivity to differences in gender and emotion in positive contrast vs. contrast-negated faces. Previous studies have shown that gender perception is mediated primarily by the fusiform gyrus, inferior occipital cortex, and cingulate gyrus (Ng, Ciaramitaro, Anstis, Boynton, & Fine, 2006), which largely overlap with the neural pathways underlying face recognition. In contrast, processing of facial expression involves both cortical and subcortical pathways (e.g. amygdala). We predicted that, like recognition, contrast-negation may impair gender discrimination. However, contrast-negation may not necessarily impair emotion discrimination. Accordingly, our participants displayed substantially decreased sensitivity to variation in gender with contrast-negation, but no change in sensitivity when discriminating levels of anger or fear. Although a t-test indicated a significant decrement in sensitivity to levels of happiness with contrast negation, the decrement was significantly less than that observed with gender and not significantly different from the non-significant decrements observed with anger and fear. Moreover, response times decreased with contrast-negation only for gender discriminations. Contrast negation destructs the otherwise highly stable ordinal luminance relations between a few face regions (Gilad, Meng, & Sinha, 2009). Our results suggest that these luminance relations may be important for gender discrimination but not necessarily for emotion discrimination, highlighting separated visual processing of facial expression.