Figure 1
(A) Tracking task setup. Participants observed a screen in which two disks representing the position of a moving target (red disk) and the position of the hand (white disk) were presented. While grasping the joint of a robotic device, participants used hand movements to control the white cursor in three possible conditions: Normal tracking (N), Delayed tracking (D), and Mechanical tracking (M). (B) Time delay (\(\tau \)) between cursor position x Cursor and hand position x Hand . C and H represent the cursor and the participant’s hand respectively. (C) Mechanical approximation to time delay. The cursor position x Cursor displayed to the participant is the result of an ordinary differential equation based on the hand position x Hand . B and K represent the damper and spring constants respectively in the mechanical system while m c and m h represent the cursor mass and the participant’s hand mass in the mechanical system respectively. (D) Experimental Conditions. The order of condition appearance for each group of participants. Each trial is represented using a rectangle with a letter symbol. ‘N’, ‘D’ and ‘M’ represent the Normal, Delay and Mechanical conditions respectively. (E) Value of delay between hand and cursor positions during the Delay condition. Delay value increased in the first 15 second of the trial (green line), stayed at a constant value for additional 80 seconds (blue line) and reduced at the end of the trial (orange line). We divided the data of the trial to 22 segments (5 second each).
