The spatial distribution of auditory attention in early blindness

Early blind people compensate for their lack of vision by developing superior abilities in the remaining senses such as audition (Collignon et al., 2006; Gougoux et al., 2004; Wan et al., 2010). Previous studies reported supra-normal abilities in auditory spatial attention, particularly for the localization of peripheral stimuli in comparison with frontal stimuli (Lessard et al., 1998; Roder et al., 1999). However, it is unknown whether this specific supra-normal ability extends to the non-spatial attention domain. Here we compared the performance of early blind subjects and sighted controls, who were blindfolded, during an auditory non-spatial attention task: target detection among distractors according to tone frequency. We paid a special attention to the potential effect of the sound source location, comparing the accuracy and speed in target detection in the peripheral and frontal space. Blind subjects displayed shorter reaction times than sighted controls for both peripheral and frontal stimuli. Moreover, in the two groups of subjects, we observed an interaction effect between the target location and the distractors location: the target was detected faster when its location was different from the location of the distractors. However, this effect was attenuated in early blind subjects and even cancelled in the condition with frontal targets and peripheral distractors. We conclude that early blind people compensate for the lack of vision by enhancing their ability to process auditory information but also by changing the spatial distribution of their auditory attention resources.