Is left always right? Directional deviations in visual line bisection as a function of hand and initial scanning direction.

Directional deviations in visual line bisection were investigated using normal subjects. Significant main effects were found for hand and initial scan direction resulting from significantly greater deviations to the left by the left hand compared with the right hand and by a scan from the left compared with a scan from the right. These results suggest that the amelioration of neglect can only be inferred from the left hand deviations of neglect patients if they are significantly leftwards of the objective middle and that the degree of leftward deviation in normal subjects results from an interaction between right hemispheric activation and unilateral allocation of attention.