Transfer of motor learning in a motion-controlled video game is better facilitated using rotations of the torso rather than movements of the center of pressure as a controller

Despite growing interest in motion-controlled video games for rehabilitation, the mechanisms that facilitate transfer of motor learning in such situations remain poorly understood. This study examined the transfer of motor learning in a video game task controlled either via center of pressure (CoP) displacement or through torso rotations. For this purpose, during the game, participants controlled an aircraft in vertical and horizontal axes and had to fly through 100 ring-shaped targets. Twenty-one participants were randomly divided into two experimental groups. The first group (CoP-Tor) played first the game controlling the aircraft with CoP displacements and then the one with torso rotations. The second group (Tor-CoP) played the games in reverse order. Spatial errors were calculated between the player's position and the targets to quantify game performance. Sample entropy of the CoP displacement was calculated to quantify repeatability in postural sway variability. Our results showed that spatial errors were significantly lower in the CoP-controlled game for the Tor-CoP group compared to the CoP-Tor group. The Tor-CoP group also exhibited lower repeatability values in the CoP-controlled game compared to the CoP-Tor group. Our results suggested a directional transfer of motor learning from the Tor-controlled game to the CoP-controlled game, because performance improved in the CoP-controlled game when it was played after a Tor-controlled game. The entropy results suggested that the improved CoP-controlled game performance was also followed by a more repeatable pattern of movement variability. Overall, our findings suggest that torso-related training can improve CoP control possibly by increasing the repeatability of movement variability.