Enhanced self-localization by auditory cues in blind humans.

PURPOSE

Investigate the involvement of auditory spatial compensation, which is observed in blind humans, in self-localization processes.

METHOD

Sighted and early-blind subjects had to indicate, on a two-dimensional view of the experimental room, the position where they previously sat and had passively listened to auditory spatial cues. Two different environments were distinguished. In a first session, auditory cues (i.e., white broadband sounds) were displayed successively in a dark anechoic room. This condition was defined as a simple acoustic environment. In a second session, four different auditory cues were displayed simultaneously at regular intervals in an experimental room, where echo cues were salient. This condition, which is more reminiscent of the natural situation, was described as a complex acoustic environment.

RESULTS

Self-localization capacities were significantly better in early-blind individuals than in sighted subjects, whatever the type of acoustic environment.

CONCLUSIONS

Auditory compensation leads to improved self-localization capacities in early-blind humans and indicates that prior visual experience is not essential for the development of spatial competence.