Visual and tactile rod bisection in unilateral neglect.

A rod bisection task was performed by 16 RBD patients with visual neglect, 10 RBD and 10 LBD patients without visual neglect, and 10 normal controls. Three different conditions were used: tactile, where they explored the rod blindfolded; visuo-tactile, where they explored the rod manually without blindfold; and visual, where they pointed to the midpoint without prior manual exploration. Only within the RBD group with visual neglect was there a significant difference between the three conditions. These patients made large rightward errors under the visual condition but no significant deviations from actual midpoint under the visuo-tactile or the tactile condition. It is therefore possible that rod exploration, which is an integral part of tactile bisection, reduces neglect to such an extent that it is difficult to identify neglect in the tactile modality on this task.