- We employed a novel technique to explore how the body's motion and morphology affect judgments of sex and gender. Stimuli depicted animated human walkers that varied in motion (gait patterns varying shoulder swagger and hip sway) and in morphology (waist-to-hip ratio). The potency of morphology in categorical sex judgments was confirmed. Visual scanning of the walkers was concentrated in the waist and hip region of the body (Study 1a). This targeted scanning was attenuated, however, when the sex of the target had been prespecified (Study 1b). Body motion permitted categorical judgments of sex, but these judgments were mediated by perceived gender (Study 2). These studies provide converging evidence for the primacy of the body's shape in categorical judgments of sex.