Sensitivity to auditory biological motion stimuli

Abstract

When one hears footsteps in the hall one instantly recognises it as a person approaching and sometimes even their identity. However, compared to visual biological motion research, auditory biological motion research is in its infancy. Here, two experiments explored sensitivity to auditory stimuli of biological and non-biological origin. First a series of signal-detection tasks compared sensitivity to three stimuli: footsteps, a ball bouncing and drumbeats. The ball controlled for translating, echoic cues; the drumbeats were matched to the walkers' cadence. Participants were no more sensitive to footsteps than to non-biological sounds. In the second experiment, participants made discriminations between pairs of stimuli (walker/ball; walker/drum; drum/ball). Participants more readily discriminated between walker versus ball, than walker versus drumbeat. Given the drum's cadence matched the walker but the ball did not, it is proposed that the perceptual invariant and critical cue for the recognition of auditory biological motion is cadence.