Extended Fitts` Law for Three-Dimensional Environment Cha, Yeon-Joo; Myung, Ro-Hae;
This study explored an extended three-dimensional Fitts` law that is more suited for the pointing task than the conventional Fitts` law. The experiments were conducted under the manipulation of the distance to the target, size of the target, and direction of the target`s location that can be described by two angles, and . Considering the starting point as the center of coordinates, is the angle between the positive z-axis and the target location and is the angle between the positive y-axis and the projected target location on the x-y plane. From the experimental results, we confirmed that all four variables significantly affect the movement time. As we extended the index of difficulty of the conventional Fitts` model by incorporating and , we established an extended Fitts` model that showed better accordance with the empirical data than the conventional Fitts` model and 3D Fitts` law of Murata and Iwase, in terms of the and the standard error of the residual between the measured movement time and the predicted value.