Neglect-associated constructional disorders: a paradoxical phenomenon?

Five neglect patients without diffuse cognitive impairment or overt constructional disabilities were asked to bisect lines and rectangles and to copy rectangles bisected in their midplane. As a group, patients showed the usual rightward bias in bisecting lines and a milder deviation in bisecting horizontally-aligned rectangles, but showed a leftward deviation of the subjective midline in the copying task. This was due to drawing the left half shorter with respect to normal controls but three patients also drew the right half longer (the total length was the same as that of controls). A possible interpretation of rectangle copying results in these three patients is that they could create a representation of the stimulus to be copied accurately enough to reproduce its total length correctly but the subjective distribution of right and left space within that representation was unbalanced. However, specific experimental work is needed to verify why our patients with mild to moderate unilateral spatial neglect overrepresented the left side in a line bisection task and underrepresented it in a copying task.