The perception of auditory motion in sighted and early blind individuals

Abstract

Motion detection is a fundamental property of the visual system that plays an important role across many of the human senses. In vision, motion processing is classically described using a motion energy model which assumes spatiotemporally selective (i.e., non-separable) filters that capture the smooth continuous change in spatial position over time afforded by moving objects. However, in the case of audition, it is still not clear whether or not the primary mechanisms underlying motion sensitivity are spatiotemporally selective. 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 non-separable. 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, with filters that were more accurate in detecting motion onsets/offsets. An ideal observer model suggested that the reliance on separable filters may be more optimal given the limited spatial resolution in auditory input.