Abstract
Purpose: Binocular vision provides an advantage for detecting and discriminating objects (i.e., binocular summation) and during reaching (i.e., higher peak velocities). However, the role of binocular vision in decision-making processes in more complex environments has not been examined. The purpose of this study was to examine the role of binocular vision during a prehension task with varied levels of difficulty. Methods: Seven, right-handed adults (age 21±1.8 years) reached and grasped a cylinder while eye movements were recorded with an eye-tracker (EyeLink) and reach kinematics with the Optotrak system. Participants had to discriminate the size of a circle shown at fixation and then pick up the corresponding cylinder (match size) from a set of cylinders. Difficulty was manipulated with set size (target shown among 3 or 6 objects) and target discriminability (using color), which were randomized during binocular (BV) and monocular viewing (MV). Results: Primary saccade latency was not affected by viewing condition or display complexity (BV: 398±97 ms; MV: 403±83 ms). Regardless of display complexity, reach latency was significantly longer during MV compared to BV (784±255 vs. 716±216 ms; p=0.016). Furthermore, set size influenced the delay in reach initiation after the primary saccade: reach initiation was prolonged during MV on average by 30 ms for the smaller set size and by 75 ms for the larger set size. Conclusion: Preliminary data support the hypothesis that binocular vision facilitates the acquisition of relevant information for decision-making to guide reaching and grasping movements. The role of this input increases in environments of greater complexity.Acknowledgments: Canada Foundation for Innovation