A study on simultaneous symmetrical motions

Three right handed male subjects performed a simultaneous symmetical task involving the motions of reach and pressing buttons. Simultaneous performance time was investigated at several symmetical locations. The symmetrical locations were defined by the combinations of different levels of separation distance, angle and distance. Three levels of separation distance (3, 9 and 15 inches), seven levels of angle (0, 15, 30, 45, 60, 75 and 90 degrees from the frontal reference plane) and three levels of distance (6.5, 11.0 and 15.5 inches) were applied to both hands equally. It was found that separation distance, angle and distance were significant factors in simultaneous performance. The performance time was increased when the symmetrical angle region was varied from the 0--45 degrees region to the 45--90 degrees region. Specifically, the performance time was at the minimum at 15 degrees of symmetrical angle and at the maximum at 90 degrees of symmetrical angle. In addition, the performance time increased not only as the distance of the moves was increased, but also as the separation distance interval was increased (i.e., the separation distance interval varied from a 3--9 inch interval to a 9--15 inch interval).