Structured Occlusion Reveals State-Dependent Smooth Pursuit Deficits Across Acute and Chronic Psychosis

Smooth pursuit eye movement abnormalities are well established in psychosis, but the specific components of pursuit performance that vary across clinical states and symptom profiles remain insufficiently characterized. Here, we used a rapid smooth pursuit paradigm combining standard linear tracking (repeated short trials moving in different directions) with structured target occlusion to examine oculomotor performance in individuals with acute psychosis, chronic psychosis, and healthy controls. The occlusion condition allowed assessment of tracking when the target was temporarily hidden and gaze had to be maintained along the expected trajectory. Basic oculomotor measures, including full pursuit gain and initial catch-up saccade properties, were largely preserved in patients. In contrast, more specific trajectory-based measures revealed distinct abnormalities. Saccade-free smooth tracking gain was selectively reduced in acute psychosis, whereas tracking deviation during non-occluded pursuit was altered in both patient groups, reflecting reduced forward tracking relative to controls. During structured occlusion, patients showed reduced forward gaze progression along the expected trajectory, with a graded pattern across groups: controls showed the strongest predictive lead, chronic patients an intermediate response, and acute patients the weakest predictive lead. Tracking deviation and occlusion-related deviation were both associated with positive symptom severity, whereas smooth tracking gain was not. These findings suggest that smooth pursuit abnormalities in psychosis are measure-specific rather than uniform, involving both broader psychosis-related alterations in gaze-target alignment and state-sensitive disruptions in occlusion-related tracking. Structured occlusion may therefore offer a useful extension of conventional smooth pursuit paradigms for probing prediction-related sensorimotor control in psychosis and distinguishing acute from chronic clinical states.