Abstract
In a recent study using spatial Bubbles (Dupuis-Roy, et al., 2009), we identified the eyes, the eyebrows and the mouth as the most potent features for face-gender discrimination (see also Brown & Perrett, 1993; Russell, 2003, 2005; Yamaguchi, Hirukawa, & Kanazawa, 1995). Intriguingly, we found that the mouth was correlated only with rapid correct answers. Given the highly discriminative color information in this region, we hypothesized that the extraction of color and luminance cues may have different time courses. Here, we tested this possibility by sampling the chromatic and achromatic face cues independently with spatial and temporal Bubbles (see Gosselin & Schyns, 2001; Blais et al., 2009). One hundred participants (35 men) completed 600 trials of a face-gender discrimination task with briefly presented sampled faces (200ms). To create a stimulus, we first isolated the S and V channels of the HSV color space for 300 color pictures of frontal-view faces (average interpupil distance of 1.03 deg of visual angle) and adjusted the S channel so that every color was isoluminant (±5 cd/m2); then, we sampled S and V channels independently through space and time with 3D Gaussian windows (spatial std = 0.15 deg of visual angle and temporal std = 23.53 ms). The group classification image computed on the response accuracy shows that in the first 100 ms, participants used the color in the mouth region along with the luminance in the left eye-eyebrow region; and that in the last 100ms, they relied on the luminance information located in the mouth and the right eye-eyebrows. Male and female observers slightly differ in their extraction of the mouth information. Altogether, these results help to disentangle the relative role of color and luminance in face-gender discrimination.