Visual search and visual target detection in patients with infarctions of the left or right posterior or the right middle brain artery.

We compared visual target detection and search performance of patient groups with infarctions of (1) the right middle brain artery (R-MBA) and with neglect; (2) the left posterior artery (L-PBA), (3) the right posterior artery (R-PBA), the latter two groups had contralesional hemianopias, or (4) with right hemisphere lesions without hemianopia or neglect. We found that: (1) The first three groups differed from the fourth (control) group in omissions. (2) The first three groups differed only in horizontal search but not in target detection. (3) No vertical search deficit was present for either group. (4) R-MBA patients found increasingly more targets in visual search from left to right, R-PBA patients had problems with the outermost contralesional column, L-PBA patients showed a generally slowed and more variable search pattern. Infarctions of left and R-PBA therefore resulted in different visual search patterns. The behavior of the patients with R-MBA is consistent with Kinsbourne's (1992) interactive inhibition theory of neglect.