Eye Tracking of Occluded Self-Moved Targets: Role of Haptic Feedback and Hand-Target Dynamics

Frederic Danion, James Mathew, J. Randall Flanagan
2017 eNeuro  
Previous studies on smooth pursuit eye movements have shown that humans can continue to track the position of their hand, or a target controlled by the hand, after it is occluded, thereby demonstrating that arm motor commands contribute to the prediction of target motion driving pursuit eye movements. Here, we investigated this predictive mechanism by manipulating both the complexity of the hand-target mapping and the provision of haptic feedback. Two hand-target mappings were used, either a
more » ... id (simple) one in which hand and target motion matched perfectly or a nonrigid (complex) one in which the target behaved as a mass attached to the hand by means of a spring. Target animation was obtained by asking participants to oscillate a lightweight robotic device that provided (or not) haptic feedback consistent with the target dynamics. Results showed that as long as 7 s after target occlusion, smooth pursuit continued to be the main contributor to total eye displacement (ϳ60%). However, the accuracy of eye-tracking varied substantially across experimental conditions. In general, eye-tracking was less accurate under the nonrigid mapping, as reflected by higher positional and velocity errors. Interestingly, haptic feedback helped to reduce the detrimental effects of target occlusion when participants used the nonrigid mapping, but not when they used the rigid one. Overall, we conclude that the ability to maintain smooth pursuit in the absence of visual information can extend to complex hand-target mappings, but the provision of haptic feedback is critical for the maintenance of accurate eye-tracking performance. The ability to predict visual consequences arising from our actions is central in daily activities. Here, we tested this ability by means of a task that required participants to track with the eyes a target that was occluded and whose motion was driven by the hand using simple or complex hand-target mappings both with and without haptic feedback. Our results showed that, despite a general drop in performance after target occlusion, smooth pursuit activity persisted under all conditions. Although haptic feedback was not critical under the simple mapping, it clearly improved performance under the complex one. We conclude that haptic feedback is critical to supplement vision when predicting the behavior of objects with complex dynamics.
doi:10.1523/eneuro.0101-17.2017 pmid:28680964 pmcid:PMC5494895 fatcat:57dtooxbqrhozldbmmrbmf3ap4