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Owino Eloka, Volker H. Franz; Effects of object shape on the visual guidance of action. Journal of Vision 2010;10(7):1089. doi: 10.1167/10.7.1089.
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© ARVO (1962-2015); The Authors (2016-present)
Many studies suggest that the perception of object shape is encoded holistically rather than analytically. However, little is known about how object shape is processed to control grasping movements. It has been proposed that visual control of action utilizes only the most relevant dimensions of an object (Ganel & Goodale, 2003).We tested whether visual control of action also takes into account information about object shape. 26 participants grasped a disk or a bar of identical lengths (bar: 4.1 cm long, disc: 4.1 cm diameter). In 20 % of the trials, the object changed its shape from bar to disk or from disk to bar during the movement. The change occurred early during the movement (after index-finger or thumb moved 2 cm away from the starting position) or late (after 2/3 of the movement distance was covered). In the remaining 80 % of the trials no object change took place. We found that maximum grip aperture depended on object shape. Participants grasped bars with a significantly larger maximum grip aperture than disks. Furthermore, they adjusted maximum grip aperture when object shape changed from bar to disk. Specifically, these adjustments occurred only in the early phase of the movement. Our results reveal that vision for action is sensitive to object shape information. They also indicate that object information encoded holistically is used for corrective adjustments during the grasping movement. Taken together, these results show that holistic processing might play a notable role in vision for action.
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