A null effect of target's velocity in the visual representation of motion with schizophrenic patients.

When people are shown a moving object that suddenly disappears and are instructed to locate its vanishing position, systematic errors in the direction of motion and in the direction of gravity are usually observed. Entitled, respectively, Representational Momentum (RepMo) and Representational Gravity, these phenomena seem to be influenced by low-level perceptual mechanisms and high-level cognitive aspects alike. Although being widely acknowledged that schizophrenic patients reveal several deficits in the perception and processing of motion, no study to date has explored these behavioral spatial mislocalizations of smoothly moving targets. The present study reports two experiments intending to fill this gap. The outcomes systematically disclosed a null effect of target's velocity for schizophrenic patients, a well established determinant of RepMo's magnitude with nonpsychiatric populations. No other variables (implied mass and motion direction) revealed this dissociation between the groups. The results are discussed within the distinction of kinematic and dynamic variables, with schizophrenic patients revealing a deficit in the processing of the former, and a link with dysfunctional smooth pursuit eye movements is suggested.