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Melissa Bulloch, Steven Prime, Jonathan Marotta; The Effects of Speed and Direction on Eye-hand Coordination for Moving Targets. Journal of Vision 2014;14(10):833. doi: https://doi.org/10.1167/14.10.833.
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© ARVO (1962-2015); The Authors (2016-present)
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 lab, utilizing stationary objects, has shown that participants initial gaze tends to be directed towards the eventual location of the index finger. This experiment examined how object movement affects gaze and selection of grasp points. A computer-generated target (4 x 4 cm) was presented on either the left or right edge of a 24 in. monitor, and after a 1.5 s delay, travelled horizontally across the monitor at either a "slow" (5 cm/s) or "fast" (10 cm/s) speed. Participants reached to grasp the target upon hearing a tone presented either 2.5 s or 5 s after the target appeared. Results showed that when the target first appeared, participants anticipated the targets eventual movement by fixating ahead of its leading edge. 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. Final fixations tended towards the final index finger contact point on the target. ROI analysis, and examination of the extent to which the eyes reproduced the targets motion, revealed that it was direction that most influenced fixation locations and grasp points. Interestingly, it was found that participants fixated further ahead of the targets leading edge when the direction of motion was leftward, particularly at the slower speedpossibly the result of mechanical constraints of intercepting leftward moving targets with ones right hand. Our findings suggest differences between initial fixation locations (an anticipation effect), but similar preference for final fixation locations, when reaching to grasp moving versus stationary targets.
Meeting abstract presented at VSS 2014
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