Shape Recognition With Sounds: Improvement in Sighted Individuals After Audio-Motor Training.

Recent studies have demonstrated that audition used to complement or substitute visual feedback is effective in conveying spatial information, e.g., sighted individuals can understand the curvature of a shape when solely auditory input is provided. Recently we also demonstrated that, in the absence of vision, auditory feedback of body movements can enhance spatial perception in visually impaired adults and children. In the present study, we assessed whether sighted adults can also improve their spatial abilities related to shape recognition with an audio-motor training based on the idea that the coupling of auditory and motor information can further refine the representation of space when vision is missing. Auditory shape recognition was assessed in 22 blindfolded sighted adults with an auditory task requiring participants to identify four shapes by means of the sound conveyed through a set of consecutive loudspeakers embedded on a fixed two-dimensional vertical array. We divided participants into two groups of 11 adults each, performing a training session in two different modalities: active audio-motor training (experimental group) and passive auditory training (control group). The audio-motor training consisted in the reproduction of specific movements with the arm by relying on the sound produced by an auditory source positioned on the wrist of participants. Results showed that sighted individuals improved the recognition of auditory shapes only after active training, suggesting that audio-motor feedback can be an effective tool to enhance spatial representation when visual information is lacking.