Abstract
The performance of three tasks—line bisection, line length discrimination, and line bisection after line length discrimination—was tested in 10 patients with left unilateral spatial neglect. To assess line length discrimination ability, a line is drawn perpendicular to a given line, and the patient judges which half of the divided line is longer. The point of subjective equality is calculated by the linear interpolation method using an ogive curve. In line bisection after a line length discrimination task, subjects are required to bisect a line immediately after they have performed a line length discrimination task.
In all patients, rightward displacement occurred less frequently in the line length discrimination task and line bisection after line length discrimination task than in the line bisection task. When the results for individual patients were examined, in 5 of the 10 patients rightward displacement occurred significantly less frequently in the line bisection task after line length discrimination than in the line bisection task. In 8 of the 10 patients, the results of judgment in the line length discrimination task were qualitatively similar to the adjustment in the line bisection task based on their experience in the line length discrimination task.
These results suggest that patients with left unilateral spatial neglect retain relatively good line length discrimination ability and that when line bisection is tested after a line length discrimination task, the patient's judgment in line bisection is appropriately adjusted on the basis of line length discrimination.
