ScienceDaily (Oct. 6, 2004) — Researchers report this week that early-onset blind individuals exhibit enhanced skill in their abilities to localize sound originating at a distance and that some of these skills are even obtained by those who lose sight as adults. The findings improve our understanding of how blind individuals use auditory information from their surroundings and offer clues to how these abilities develop.

Previous research had shown that blind individuals are superior to sighted individuals when it comes to tasks involving sound localization in their immediate surroundings--so-called near space. It has been suggested that calibration of sound information from near space could be achieved through information derived from touch or, in blind individuals, through the use of a cane. If this were the case, the abilities of blind people to localize sound in space would not extend beyond the reach of an arm or a cane. However, when researchers recently tested this hypothesis by exploring the ability of blind people to localize a sound source in far space, they found that blind individuals not only had spatial abilities similar to those of sighted subjects but also were superior to the sighted in several aspects of spatial localization of sound. The new work is reported by a group of researchers headed by Franco Lepore at the University of Montréal.

Taking these findings further, the researchers showed that late-onset blind individuals demonstrated the same superior spatial abilities as those that had lost their vision early in life, even though it has long been believed that only blind individuals who lose their sight early in life possess the developmental potential to develop superior abilities in the remaining senses to compensate for the loss of vision. Taken together, the findings indicate that both early- and late-onset blind individuals are able to correctly calibrate far auditory space and that these abilities, which are in some instances superior to those of sighted people, do not depend on information received through proprioception (sensory-motor feedback). Rather, it would appear that blind individuals are somehow able to use subtle acoustic cues more efficiently than sighted individuals.

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Patrice Voss, Maryse Lassonde, Frederic Gougoux, Madeleine Fortin, Jean-Paul Guillemot, and Franco Lepore: "Early- and Late-Onset Blind Individuals Show Supra-Normal Auditory Abilities in Far-Space"

Publishing in Current Biology, Volume 14, Number 19, October 5, 2004, pages 1734–1738.

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