Improved selective and divided spatial attention in early blind subjects.

Spatial attention paradigms using auditory or tactile stimulation were used to explore neural and behavioral reorganization in early blind subjects. Although it is commonly assumed that blind subjects outperform sighted subjects in such tasks, the empirical data to confirm this remain controversial. Moreover, previous studies have often confounded factors of sensory acuity with those of attention. In the present work, we compared the performance of individually matched early blind and sighted subjects during auditory and tactile tasks. These consisted of sensory acuity tests, simple reaction time task as well as selective and divided spatial attention tasks. Based on sensory measurements, we made sure that the reliability and salience of auditory and tactile information were identical between the two populations to estimate attentional performance independently of sensory influence. Results showed no difference between groups in either sensory sensitivity or simple reaction time task for both modalities. However, blind subjects displayed shorter reaction times than sighted subjects in both tactile and auditory selective spatial attention tasks and also in bimodal divided spatial attention tasks. The present study thus demonstrates an enhanced attentional performance in early blind subjects which is independent of sensory influence. These supra-normal abilities could be related to quantitative and qualitative changes in the way early visually deprived subjects process non-visual spatial information.