Neglect between but not within auditory objects

Unilateral neglect is frequently characterized by the presence of extinctio n, which is a lack of awareness to contralesional visual stimuli in the pre sence of those further towards the ipsilesional side. It has been establish ed that this visual extinction can be reduced if the stimuli are grouped to gether into a single object. However, attention between and within auditory objects has never before been studied. We demonstrate for the first time t hat unilateral neglect-hitherto thought primarily to be a disorder of visuo spatial processing-involves a specific deficit in allocating attention betw een auditory objects separated only in time and not in space. Importantly, this deficit is restricted to comparisons between sounds: the patients' abi lity to make within-sound comparisons is similar to chat of controls. These differences cannot be explained in terms of different time spans over whic h comparisons must be made. The results suggest unilateral neglect is linke d to-if not actually determined by-a reduction in attentional capacity in b oth the visual and auditory domains, and across the dimensions of both spac e and time. The findings have potential clinical applications.