Grasping moving objects involves both spatial and temporal predictions. The hand is aimed at a location where it will meet the object, rather than the position at which the object is seen when the reach is initiated. Previous eye–hand coordination research from our laboratory, utilizing stationary objects, has shown that participants’ initial gaze tends to be directed towards the eventual location of the index finger when making a precision grasp. This experiment examined how the speed and direction of a computer-generated block’s movement affect gaze and selection of grasp points. Results showed that when the target first appeared, participants anticipated the target’s eventual movement by fixating well ahead of its leading edge in the direction of eventual motion. Once target movement began, participants shifted their fixation to the leading edge of the target. Upon reach initiation, participants then fixated towards the top edge of the target. As seen in our previous work with stationary objects, final fixations tended towards the final index finger contact point on the target. Moreover, gaze and kinematic analyses revealed that it was direction that most influenced fixation locations and grasp points. Interestingly, participants fixated further ahead of the target’s leading edge when the direction of motion was leftward, particularly at the slower speed—possibly the result of mechanical constraints of intercepting leftward-moving targets with one’s right hand.
Eye–hand coordination Moving objects Fixation locations Grasping Visuomotor control
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This research was supported by the Undergraduate Student Research Award (USRA) from the Natural Science and Engineering Research Council of Canada (NSERC) and the University of Manitoba’s Undergraduate Research Award held by M.C.B, and a grant from NSERC held by J.J.M. Special thanks are due to Amir Meghdadi for his programming support.
Compliance with ethical standards
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
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