Analysing non-motor bias in unilateral neglect with a new variant of the line bisection task

PRIMARY OBJECTIVE: To develop a new variant of the line-bisection task for assessing non-motor (attentional, representational, etc.) bias in unilateral neglect (UN), i.e. the exactly bisected line selection task (EBLST). METHODS AND PROCEDURES: Nine patients with UN were included in this study. In the EBLST, multiple horizontal lines, bisected in various proportions, were presented. The participants chose the most equally bisected line and then pointed to the bisector of the chosen line. To avoid the influence of motor bias, the participants used perceptual judgement first. The conventional line-bisection task was also performed. The deviation of the subjective midpoint was measured for each participant in both tasks. MAIN OUTCOMES AND RESULTS: Eight participants showed obvious rightward deviation in the EBLST, thus resulting in being classified as patients with non-motor neglect. Five participants showed greater deviation in the EBLST than in the line-bisection task. CONCLUSION: Non-motor function in patients with UN was successfully assessed by the EBLST.