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Claudia L.R. Gonzalez, Liana E. Brown, Melvyn A. Goodale; No visual field advantage for visually-guided grasping movements made with the left hand. Journal of Vision 2008;8(6):303. doi: 10.1167/8.6.303.
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In a series of recent studies we compared the performance of the right and left hands when participants grasped targets embedded in illusory backgrounds. We found that compared to the right, the left hand displayed a much larger effect of the size illusions and this sensitivity was present in both right- and left-handers. The results led us to suggest that the left hemisphere is specialized for visuomotor actions. In the present work we expand this notion by showing a right-hand advantage for grasping outside the context of perceptual illusions. Participants either grasped or estimated the size of different target objects while fixating on one of 8 randomly-presented LEDs. The LEDs were arranged radially in four directions and at two eccentricities around the central target location. We replicated previous findings of a lower visual field advantage for prehension when participants used their right hand to grasp the different targets. When they used their left hand, however, no lower field advantage was detected. In other words, grasping movements made with the right hand to objects appearing in the lower visual field were less variable than similar movements made to objects appearing in the upper visual field. Left-hand movements were more variable overall than right-hand movements, and this high variability was the same in the upper and lower visual fields. No differences between the hands or across visual fields were detected when participants had to adjust their thumb and index finger to estimate the size of the targets. We see these results as new evidence supporting the notion of a left-hemisphere specialization for the visual control of skilled movements.
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