Fig. 1

Experimental setup. a side and top views of subject position during data collection. b definitions of radial and tangential errors for the force matching and target reaching tasks. c–e are three sensorimotor tasks tested. Each thin trace is a trial. c Force matching: Subject generates a 10 N force vector against the robotic handle in locked mode, first with the feedback cursor visible, and then subject generates the same force vector with the feedback cursor invisible. The feedback cursor represents the force vector. d Target reaching: The subject moves the robotic handle from a start position to a target position. The feedback cursor representing hand position is visible when there is visual feedback and invisible when there is no visual feedback. e Postural stability: The subject stays within a start position for 5 s while resisting a 5 N-force vector from the robot. The feedback cursor represents the hand position, and the visibility is randomly assigned to be visible or invisible