DISPARITY VERGENCE EYE-MOVEMENTS EXHIBIT PREPROGRAMMED MOTOR CONTROL

To determine the control strategy used to mediate disparity vergence e ye movements, an optical technique was employed which eliminated the v isual feedback normally associated with a vergence movement. The resul ting ''open-loop'' vergence responses from four subjects exhibited mul tiple step-like movements. This finding augments previous demonstratio ns of multiple-step tracking strategies in vergence eye movements and supports the theory that the initial portion of the vergence response is under preprogrammed control. Additional evidence for preprogramming is given by the similarity of the initial dynamics between open- and closed-loop responses as evidenced by similar ratios of peak velocity to amplitude (i.e. ''main sequence'' plots).