Processing of auditory information by the blind in spatial localization tasks.

Abstract

Spatial localization of sonorous targets in the near space, by blindfolded sighted subjects and by early- or late-blind subjects, was investigated using a two-dimensional coordinate system (direction and distance) in various experimental conditions: The head was free or restrained, and the subject’s response was either a finger pointing on a coordinate grid in open loop or a verbal assessment based on a simple reference system. The results for each group of subjects were processed by dealing separately with distance and direction parameters. They show that with early blinds, only the distance evaluation was particularly impaired. Performance did not seem to depend much on whether the head was restrained or free. Finally, direction was best evaluated by motor responses, whereas distance was more accurately judged verbally.