[An experimental study of work load on VDT performance. Part 2. Effects of difference in input devices]

Effects of the difference in input device on work load of VDT task were studied. The subjects of the experiment were eight healthy male college students (age: 21-22 yr) having a binocular vision of not less than 0.7 and no astigmatism or hyperopia. The test consisted of an experimental word processing task in which the subjects visually searched e's in given sequences of alphabetical letters displayed on the CRT and converted them to 5's through input device operation. As for experimental conditions, two kinds of input devices, namely, keyboard and lightpen were adopted and 1 h was provided as each operation time. Critical flicker fusion (CFF), near point distance, accommodation time, subjective fatigue symptoms, blinking counts, pupillary reflex, electromyogram in upper limb, neck and shoulder and performance score were measured. The results were as follows. Decrease in C.F.F. was observed in two experimental conditions during the process of operating time. Increments in complaints of subjective fatigue related to visual function were seen in the two experimental conditions after 1 h VDT task. A higher error rate in performance was observed in the subjects using the lightpen compared to the one using the keyboard. The frequency of both blinking and pupil-size changes were lower in the subjects using the lightpen compared to those using the keyboard. This suggests that the gaze time of the VDT screen with lightpen-condition is longer than that in keyboard-condition.(ABSTRACT TRUNCATED AT 250 WORDS)