Dissociated neglect for objective and subjective sizes.

We examined the effect of line length and viewing distance on the line bisection performance in near space in five patients with left unilateral spatial neglect following right parietal lesions. A line bisection task by fixation was devised to avoid the influence of manual responses. The rightward deviation measured in visual angle increased linearly as a function of the visual angle of lines 150 mm or more long. This linearity, however, did not hold for lines of 100 mm or less. The deviation measured in length was nearly constant for each of these short lengths, even when the visual angle was varied at different viewing distances. The patients therefore discriminated the objective lengths of the short lines. For small objects, neglect patients may distribute attention mainly on the coordinates scaled for objective size.