title: Control strategy of hand movement depends on target redundancy.
abstract: Reaching toward a point target has been intensively studied in human motor control. However, little is known about reaching toward a redundant target, such as grasping a bar, in which the grasping point is irrelevant to the achievement of a task. We examined whether humans could solve the target-redundancy and control problems in a serial fashion or control their body without solving the target-redundancy problem. We equalized the target ranges between two reaching tasks: a point-to-point reaching task without target-redundancy and a point-to-bar reaching task with target-redundancy. In the both tasks, we measured hand viscoelasticity at movement end as parameters that reflect the adopted control strategy. As a result, the hand viscoelasticity in the point-to-bar reaching task was smaller than that in the point-to-point reaching task, even under the same kinematics. These results indicate that the hand viscoelasticity was modulated depending on the target-redundancy. Moreover, it is suggested that a human reaches toward a redundant target by effectively utilizing information of target redundancy rather than explicitly solving the target-redundancy problem.
authors.affiliation: Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan.|Cognitive Mechanisms Laboratories, Advanced Telecommunications Research Institute International, Kyoto, Japan.
authors.forename: Shunta
authors.initials: S
authors.lastname: Togo
authors.affiliation: Cognitive Mechanisms Laboratories, Advanced Telecommunications Research Institute International, Kyoto, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Yoshioka
authors.affiliation: Cognitive Mechanisms Laboratories, Advanced Telecommunications Research Institute International, Kyoto, Japan.|Department of Psychology, The University of Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imamizu
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006225:Hand; D006801:Humans; D008297:Male; D009043:Motor Activity; D011597:Psychomotor Performance; D055815:Young Adult