Fig. 2

Experimental setup and protocol. a Participant at robot holding the end effector of a planar manipulandum, with integrated forearm support. An opaque screen occluded direct visual feedback of task performance; the left arm shows the standard placement of the four tactors (red dots). b Tasks. Left: stabilizing the hand at a fixed point in space against robotic perturbations. Right: example of a center-out reaching movement. c Sequence of events in each experiment. E1: Experiment 1. E2: Experiment 2; baseline 2 and test 2 were counter balanced in order across participants. Visual feedback (V) and vibrotactile feedback (T) was either continuous (+), absent (−), or only used for providing the results at the end of each task (KR). This sequence was used during 2 sessions, in which the only difference was that the vibration feedback encoded either error or state