Experimental protocol

Participants sat on a chair with the Graded Repetitive Arm Supplementary Program manual placed on a table in front of or beside them. All exercises were performed while sitting on a chair with arm rests. A custom software application was used to display visual feedback on a television monitor 2 m in front of the participant. The Kinect sensor was mounted on a tripod to the left side of the monitor (Figure 1). For exercises that required a table, the table was placed in front of the participants. Prior to the experiment, a researcher demonstrated the protocol for the Graded Repetitive Arm Supplementary Program to each participant and confirmed they were able to perform the assigned exercises independently. Videos and joint positions of participants were tracked and recorded at 30 frames per second throughout all exercises.

Experimental setup of performing exercises in (a) no feedback, (b) video feedback, and (c) avatar feedback conditions. For anonymity, the face of the volunteer (not a participant) illustrating the setups is blocked off in (b).

Each participant was asked to perform the exercises in front of a computer monitor under three different conditions in three separate visits approximately one week apart. The three conditions were:

Phase A (no feedback): The monitor was turned off and participants were asked to only focus on the exercises. The Kinect sensor was used for recording purposes only (Figure 1(a)).

Phase B (video feedback): The live video of the participants doing exercises recorded from the Kinect camera was displayed on the monitor in real time. Participants were asked to pay attention to the screen during each exercise whenever possible (Figure 1(b)).

Phase C (avatar feedback): C was similar to B, except that participants' movements were displayed as an avatar instead of a video (Figure 1(c)).

The order of the phases varied among the participants to include all permutations; e.g. ABC, ABC, BAC, etc.