Eye tracking a self-moved target with complex hand-target dynamics

Abstract

Previous work has shown that the ability to track with the eye a moving target is substantially improved when the target is self-moved by the subject's hand compared with when being externally moved. Here, we explored a situation in which the mapping between hand movement and target motion was perturbed by simulating an elastic relationship between the hand and target. Our objective was to determine whether the predictive mechanisms driving eye-hand coordination could be updated to accommodate this complex hand-target dynamics. To fully appreciate the behavioral effects of this perturbation, we compared eye tracking performance when self-moving a target with a rigid mapping (simple) and a spring mapping as well as when the subject tracked target trajectories that he/she had previously generated when using the rigid or spring mapping. Concerning the rigid mapping, our results confirmed that smooth pursuit was more accurate when the target was self-moved than externally moved. In contrast, with the spring mapping, eye tracking had initially similar low spatial accuracy (though shorter temporal lag) in the self versus externally moved conditions. However, within ∼5 min of practice, smooth pursuit improved in the self-moved spring condition, up to a level similar to the self-moved rigid condition. Subsequently, when the mapping unexpectedly switched from spring to rigid, the eye initially followed the expected target trajectory and not the real one, thereby suggesting that subjects used an internal representation of the new hand-target dynamics. Overall, these results emphasize the stunning adaptability of smooth pursuit when self-maneuvering objects with complex dynamics.

Prediction in goal-directed action

“…For example, smooth pursuit is generally enhanced if gaze is directed at a target that is actively moved by the observer's hand (Gauthier & Hofferer, 1976;Gauthier, Vercher, Mussa Ivaldi, & Marchetti, 1988). This finding indicates that the oculomotor system might have access to a limb efference copy signal (Ariff, Donchin, Nanayakkara, & Shadmehr, 2002) and might use an internal representation of the dynamics of the hand to control the eye (Landelle, Montagnini, Madelain, & Danion, 2016). Consistent with these assumptions, smooth pursuit can be enhanced by haptic feedback during target occlusion (Danion, Mathew, & Flanagan, 2017).…”

Gaze behavior during visuomotor tracking with complex hand-cursor dynamics

“…These values are about one third of values used in previous studies investigating the manipulation of nonrigid objects (Danion et al, 2012;Dingwell et al, 2002;Dingwell, Mah, & Mussa-Ivaldi, 2004;Landelle et al, 2016;Nagengast et al, 2009), but a similar parameter setting was used in our recent study (Danion, Mathew, & Flanagan, 2017). The rational for decreasing object inertia was to prevent possible fatigue effects while keeping a 1 Hz resonance frequency as in other studies; the resonance frequency (F) of a massspring system depends on its mass (m) and its stiffness (k) such that…”

“…To better characterize saccadic activity we computed for each trial the mean saccade rate (average number of saccades per second). To evaluate the performance of smooth pursuit, we computed its mean tangential velocity as well as its gain (SP gain) by averaging the ratio between instantaneous gaze and target tangential velocities (only situations where target tangential velocity was greater than 10 cm/ s were considered; Landelle et al, 2016). Finally, to assess the relative contribution of saccades and smooth pursuit, for each trial we computed the total distance traveled by the eye with saccades and then expressed this as a percentage of the total distance traveled by the eye using both saccades and smooth pursuit (Orban de Xivry et al, 2006;Landelle et al, 2016).…”

“…We asked participants to move a cursor controlled by the hand. In the spring condition, the cursor that behaved like a mass attached to the hand by means of a spring (Danion, Diamond, & Flanagan, 2012;Dingwell, Mah, & Mussa-Ivaldi, 2002;Landelle, Montagnini, Madelain, & Danion, 2016;Nagengast, Braun, & Wolpert, 2009). We examined hand and gaze behavior during both initial learning and subsequent steady state performance.…”

Limited Contribution of Primary Motor Cortex in Eye-Hand Coordination: A TMS Study

“…It is well established that smooth pursuit (SP) eye movements are substantially improved when the viewed target is moved by the subject's hand compared with when it is moved by an external agent as reflected by a higher SP gain, fewer saccades, and a shorter eye-target lag (Steinbach and Held, 1968;Angel and Garland, 1972;Gauthier et al, 1988;Vercher et al, 1995;Chen et al, 2016;Landelle et al, 2016). Furthermore, accurate SP of a self-moved target is possible in the absence of vision (Gauthier and Hofferer, 1976) and in deafferented patients (Vercher et al, 1996). To account for these observations, a leading hypothesis is that the oculomotor system benefits from hand motor signals (Steinbach and Held, 1968;Vercher et al, 1996).…”