Eye tracking and psychopathology. New procedures applied to a sample of normal monozygotic twins

New methods for examining eye movements were developed and applied in a study of young, adult monozygotic twins. Subjects, tested twice, engaged in smooth pursuit tracking at different target frequencies, followed a stimulus requiring saccadic eye movements, performed a related psychomotor hand tracking task, and tracked a target while monitoring changes in the stimulus display. Analysis of test-retest reliability and twin concordance suggested that performance on these tasks characterized stable traits and were consistent with other reports implicating a genetic contribution to tracking ability. Special consideration was given to the probable role of attention in producing various types of tracking deficit. Estimates of the incidence of tracking dysfunction and correlations with psychometrically measured personality traits were examined.