Abstract
Eye-hand coordination is a particularly interesting ability because the control plants for effecting each action are distinct and specialized in some aspects – efferent pathways, sensorimotor integration – while their organization overlaps at other levels – serial and temporal planning – of organization. We developed a novel task to investigate whether online spatial interference exists between the coding of eye and hand movements, and if it might be modulated by their respective demands on motor planning. Participants responded to acoustic and visual stimuli with finger taps and saccades. The primary axes of saccades (left-right) and finger taps (up-down) were orthogonal, and we examined the secondary axis of the finger trajectory kinematics for evidence of spatial interference caused by, and spatially congruent to saccades. Experiment 1 required synchronous and periodic tapping and saccading and our results confirmed that both actions were predictive relative to the timing goal, suggesting that temporal parametrization was dependent on a shared goal specified in planning. Saccades in Experiment 2 were non-periodic and timed pseudo-randomly with respect to tapping. We confirmed this evoked reactive saccades in parallel to predictive tapping, which substantiates the separation of these actions at the level of temporal and serial order planning. We observed spatial interference in form of small finger deviations congruent with the saccades, a novel finding that demonstrates coding overflow between action systems. Interestingly, the interference presented differently in the two experiments, and we conclude that different pathways mediate interference depending on the respective goals of each action.Acknowledgments: Sensorimotor and MiNDS labmates, OGS - Susan Morag McNeill Cameron Scholarship