A bias for the female face in the right hemisphere

In the present study we assessed the contribution of the two hemispheres to the attribution of gender of faces in male and female observers. Normal and chimeric faces were presented in their canonical orientation and upside-down in a tachistoscopic paradigm. Chimeric faces were composed of two halves (left and right) obtained from photos of individuals of the same sex or from individuals of different sexes. All faces were presented tachistoscopically with a central fixation, the two halves falling in the two visual fields of the observer, who was required to rapidly judge the sex of the face. A left half-face (right-hemispheric) bias for gender attribution with upright faces was observed both in male and female participants, as previously reported. Strikingly, however, the bias depended entirely on female-left/male-right chimeras, revealing a right-hemispheric advantage for the recognition of female faces. The results are discussed in the light of a behavioural bias during development (i.e., maternal cradling).