Diagonal neglect on cancellation.

Patients with right hemisphere injury frequently neglect to cancel targets primarily in the left part of the page nearest the body. Since this region is diagonally opposite the area from where such patients usually begin cancelling, near left ('diagonal') neglect may be consequent to stimulus order effects ('fatigue'). We evaluated the persistence of near left neglect in nine stroke patients when they had to cancel either the near or the far half of the page before proceeding to the other half. Our results showed that near left neglect on the page was largely unaffected by cancellation order. Furthermore, a near left gradient of omissions was established within both radial (near and far) halves of the page, as well as for the entire page. Our findings suggest that diagonal cancellation neglect is unrelated to fatigue and reflects a consistent, two-dimensional disorder of spatial attention. Such neglect may be related to the extent of the visible stimulus array, as well as to the array's location in egocentric space.