Smooth pursuit eye movements in the parents of schizophrenics

Smooth pursuit eye movements and fixation were studied, using quantitative techniques, in eight parents of chronic schizophrenics. Only one subject showed a statistically significant excess of square wave jerks (SWJ) and other saccadic intrusions during fixation. All subjects were capable of normal smooth pursuit gains during ramp pursuit. Six subjects, however, made 'anticipatory saccades' which took the eyes ahead of the target; they spent considerable time fixating off-target. These hitherto undescribed movements, which superficially resemble SWJ, appear to represent an involuntary attentional disturbance in these clinically normal individuals.