Eye movements in visual search indicate impaired saliency processing in Parkinson's disease

Previous studies have produced contradictory evidence on the nature of the visual search impairment in patients with Parkinson's disease (PD). Eye movements were measured during multi-target search in nine individuals with mild-to-moderate PD. Subjects were asked to click on a response button whenever they judged they were fixating a target for the first time. Compared to age-matched healthy volunteers, PD patients were impaired at efficient search (detecting "+"s amongst "L"s) but not inefficient search ("T"s amongst "L"s). However, these patients had normal memory for locations as indexed by their rate of re-clicking on previously inspected locations. We suggest that the pattern of gaze for efficient search may reflect impaired saliency processing in PD.