Generation of synthetic male and female walkers through manipulation of a biomechanical invariant.

Synthetic versions of human walkers were generated by computer as point-light displays. Previously it had been determined that the natural gaits of males and females differ according to the extent of movement at the shoulder and the hip. These movements were measured and then used to synthesize the stimuli used in the present study. These stimuli are shown here to be identified by untrained viewers as male when the shoulder movement is greater than the hip movement, and female when the configuration is reversed. Because of the coherence of the display lights representing the shoulder and hip are not necessary for gender recognition, although they do increase performance level. Hypernormality and heavy-footedness in gait are also discussed. Finally, all results are linked to an underlying biomechanical invariant, the center of moment.