Eye-movements in virtual bisection task: new evidences of neglect syndrome?

Introduction Severity of visual neglect syndrome seems to be related to assessment tasks. Concerning bisection line authors find different spatial-location biases in relation to segment length, line spatial localisation and its visual availability (solid line vs unfilled gap). Our aim is try to understand mechanisms of visual exploration in accordance to eye-movement in a specific task. Material and method Participants: three post-acute right-brain damaged patients with left neglect and no other problem such as dementia, psychiatric disorders and global attentional deficit or general illness which could prevent to undergo to computerized experimental sessions; and 10 control subject matched for age and education. Participants were asked to indicate midpoint in an unfilled gap between to endpoints. All item varied in length and spatial position. Result Main analysis were conducted on bisection performance, RTs and eye movements with two factor repeated-measure ANOVAs (group*segment length and group*spatial location). We found main effect of group and significant interaction effects. Patients show higher rightwards fixation movements (F(1,11)=7.78, p<.001) and fixation duration (F(1,11)=12.45, p<.001). Further statistical analysis showed worst performance and reduction of leftwards eye-movents only for extremely left stimuli. Conclusion Aside from confirm a rightward bias, we observed an extreme-left gradient effect which should be took in consideration for carring out of cognitive rehabilitation tasks involving eye-movements as instrument to let patients aware of their deficit.