Charlotte presented her research at the Vision Sciences Society meeting in St. Petersburg Beach, Florida. Poster.
Perception and Action Lab, Dept. of Psychology, University of Manitoba |
| When performing a visually-guided grasp to a moving object, spatial and temporal predictions must be made so that 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. Last year at VSS, we presented a translational movement study, where we showed that participants fixated the leading edge of a moving target until they initiated their reach, at which point they shifted their gaze to the eventual index finger contact position on the object, above the centre of mass (COM) (Bulloch, Prime & Marotta, 2014). This year, we investigated rotating targets. Do participants track one position on the target while it rotates, or do they shift their gaze to new potential grasping sites as they become available throughout the tracking phase? A 6.2 cm x 10.2 cm computer-generated Efron block (Efron, 1969) was rotated about its COM at one of two speeds (50 deg/s and 30 deg/s). After a delay of 3.5 seconds, participants received a “go” tone and reached out and “grasped” the block. Upon contact with the screen, the block stopped its rotation. Gaze fixations during the delay, and during the reach itself, favoured the left half of the block, above the COM, suggesting that every time a new “top edge” of the block rotated clockwise into position, it became the salient fixation point. These results suggest that anticipated grasping positions on a rotating object are constantly changing due to kinematic constraints (e.g. wrist extension) as the block rotates.  |
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