Figure 1
From: The visual geometry of a tool modulates generalization during adaptation
Experimental setup. (A) Subjects grasped the handle of the WristBot and rotated a virtual hammer-like object back and forth between two angular targets (two rectangular bars separated by 40°). (B) The object consisted of a mass (m) on the end of a rigid rod (length r). The mass of the object was set to 1% of the subject’s body mass. Subjects grasped the object by a handle at the other end of the rod and rotated the object while trying to prevent translational movement of the handle. The dynamics of the object consisted of a torque (τ) due to the moment of inertia as well as translational forces (F) due to the circular motion of the mass that perturbed the handle of the object21. (C) Three types of trials were used. Subjects experienced the torque on all trials. On exposure trials subjects experienced translational forces. On zero-force trials, the handle was free to move. The kinematic error (KE) of the handle during the rotation was measured on exposure and zero-force trials. On error-clamp trials, the handle was fixed in place using a simulated spring that prevented translational movement. On these trials we measured the compensatory forces.
