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Multiple grasp-specific representations of tool dynamics mediate skillful manipulation.

Ingram, JN and Howard, IS and Flanagan, JR and Wolpert, DM (2010) Multiple grasp-specific representations of tool dynamics mediate skillful manipulation. Curr Biol, 20. pp. 618-623.

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Abstract

Skillful tool use requires knowledge of the dynamic properties of tools in order to specify the mapping between applied force and tool motion. Importantly, this mapping depends on the orientation of the tool in the hand. Here we investigate the representation of dynamics during skillful manipulation of a tool that can be grasped at different orientations. We ask whether the motor system uses a single general representation of dynamics for all grasp contexts or whether it uses multiple grasp-specific representations. Using a novel robotic interface, subjects rotated a virtual tool whose orientation relative to the hand could be varied. Subjects could immediately anticipate the force direction for each orientation of the tool based on its visual geometry, and, with experience, they learned to parameterize the force magnitude. Surprisingly, this parameterization of force magnitude showed limited generalization when the orientation of the tool changed. Had subjects parameterized a single general representation, full generalization would be expected. Thus, our results suggest that object dynamics are captured by multiple representations, each of which encodes the mapping associated with a specific grasp context. We suggest that the concept of grasp-specific representations may provide a unifying framework for interpreting previous results related to dynamics learning.

Item Type: Article
Uncontrolled Keywords: Bioengineering Biomechanical Phenomena Feedback, Sensory Hand Strength Humans Motor Skills Robotics User-Computer Interface
Subjects: UNSPECIFIED
Divisions: Div F > Computational and Biological Learning
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:33
Last Modified: 24 Mar 2014 01:13
DOI: 10.1016/j.cub.2010.01.054

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