Perceptual and premotor components of unilateral auditory neglect

Recent investigations have distinguished between ophthalmokinetic and melokinetic factors of unilateral neglect. The aim of our study was to investigate the possible dissociation between melokinetic (premotor) and perceptual factors, avoiding any overt oculokinetic components. We asked four blindfolded left neglect patients to set a dichotic sound in central position, by moving a handle controlling the difference of intensity between the sounds delivered to the left and to the right ears. Two conflicting conditions were used. In the congruent condition, the sound moved in the same direction as the hand movement; in the noncongruent condition, it moved in the opposite direction. One patient performed as if suffering from melokinetic neglect, and another as if suffering from perceptual neglect. The behavior of the other two subjects did not lend itself to a clearcut interpretation.