Before the experiment, the 120 subjects needed to learn how to
use the new GUI. At first, the subjects were asked to scroll the
wheel up and down once with the pointer on the tool ball. The total
time to complete the above operation process was recorded.
Secondly, the subjects repeated the above process and the average
times of the two operations were calculated. The subjects executed
the operation a total of five times, and a simple learning curve was
drawn (Fig. 8). Since the operations of wheel scrolling are short and
routine, only a modest amount of improvement occurs during the
first few repetitions. As the numbers of repetitions increases, the
average time of each operations decreases from 1.18 (sec.) to 0.58
(sec.). Fig. 8 illustrates the relationship between increasing repetitions
and decreasing time per repetition. In addition, since scrolling
the mouse wheel is a common action for most subjects, only a few
subjects made errors throughout the entire task.