The perception of auditory motion in sighted and early blind individuals

Abstract

Motion perception is a fundamental sensory task that plays a critical evolutionary role. In vision, motion processing is classically described using a motion energy model with spatiotemporally nonseparable filters suited for capturing the smooth continuous changes in spatial position over time afforded by moving objects. However, it is still not clear whether the filters underlying auditory motion discrimination are also continuous motion detectors or infer motion from comparing discrete sound locations over time (spatiotemporally separable). We used a psychophysical reverse correlation paradigm, where participants discriminated the direction of a motion signal in the presence of spatiotemporal noise, to determine whether the filters underlying auditory motion discrimination were spatiotemporally separable or nonseparable. We then examined whether these auditory motion filters were altered as a result of early blindness. We found that both sighted and early blind individuals have separable filters. However, early blind individuals show increased sensitivity to auditory motion, with reduced susceptibility to noise and filters that were more accurate in detecting motion onsets/offsets. Model simulations suggest that this reliance on separable filters is optimal given the limited spatial resolution of auditory input.