Visual search patterns in neglect: comparison of peripersonal and extrapersonal space.

Previous studies of visual search patterns in visuospatial neglect have analyzed shifts of attention during search tasks using eye tracking technology and verbal reports. The purpose of the present study was to replicate and extend upon reported parameters of visual scanning patterns of neglect patients in peripersonal space (within arms reach) and to examine whether similar patterns of visual search are also apparent in extrapersonal space (beyond arms reach). Using a simple verbal visual search and target detection paradigm right-hemisphere stroke participants, with and without neglect, and healthy older volunteers named targets on scanning sheets placed in peripersonal and extrapersonal space. The healthy controls and right-hemisphere stroke group without neglect showed similar 'reading' type strategies, while the neglect group displayed an unsystematic search pattern, during search in both peripersonal and extrapersonal space. Group comparisons of search parameters support the presence of multiple cognitive deficits affecting the complex visual search patterns of neglect patients, including a rightward attentional bias, a reduced spatial scale of attention (local processing bias), and a deficit of working memory affecting both near and far space search. Ventral visual stream damage and neglect, however, were related to slower target report rate and more misidentification errors in extrapersonal space. The ease of administration of this verbal target detection task in both peripersonal and extrapersonal space, and the relationship of the measures produced to theorized attentional and executive deficits in neglect, provide impetus for further research on the severity and independence of individual scanning deficits in neglect.