Auditory attention and blindness: Visual imaginary and head-centered meridian effects

Two experiments examined auditory spatial attention orienting in three groups of subjects: normal-sighted, congenital blind, and acquired blind. In Experiment 1, subjects were required to stare an imaginary point placed straight ahead on the vertical head-centered meridian, and to detect an auditory target preceded by an endogenous auditory cue, which could be in the same or in a different location of target, with or without crossing the vertical meridian. Results showed no significant differences for blind subjects between crossing and no crossing conditions. Conversely, normal-sighted subjects showed slower RTs when cued and target locations were at the opposite sides of head-centered meridian, in agreement with previous studies that found a similar effect in the auditory modality (Ferlazzo et al., 2002). In Experiment 2, subjects were required to stare an imaginary point placed on one side (vertical visual imaginary meridian) and to carry out the same task of Experiment 1. In this case, RTs were slower in crossing conditions, for both blind and normal-sighted subjects. Moreover, in both experiments congenital blinds’ performance was better than acquired blinds, putting in evidence the greater ability of this former group in the auditory modality; while acquired blinds’ performance was more similar to normal-sight subjects