Figure 1.

Computer tasks used in the study: (1) click, (2) steer, and (3) drag and drop. Different combinations of width (W) and distance (D) were randomly presented (see Table 1). In the click trials, subjects had to click anywhere on the blue rectangle first and then the yellow rectangle. In the steer trials, subjects had to hold down the left key and steer across the distance between the two rectangles. In the drag-and-drop trials, subjects had to click on the green rectangle, hold it, drag it, and then drop it over the red rectangle.