ADJUSTMENTS OF POSTURE AND VIEWING PARAMETERS OF THE EYE TO CHANGES IN THE SCREEN HEIGHT OF THE VISUAL-DISPLAY TERMINAL

To understand the motions caused by the interaction among the differen t body parts, adjustments of both eye position and body posture to scr een height settings of 80, 90, 100, 110 and 120 cm were determined in 10 subjects. The subjects engaged in a non-keyboard, interactive compu ter game requiring constant visual monitoring. Changes in body positio ns were determined by video image analysis for the posture parameters and by video frame analysis for the eye parameters. Analysis of varian ce and correlation analysis showed that neck angle, thoracic bending a nd vertical eye position were significantly affected by changes in the screen height of the VDT. The study of the interrelationship of eye p osition and body posture suggested that changes in body positions serv ed to complement the eye position in attaining a better view of the vi sual target. Viewing angle was observed to be decided mainly by inclin ation of the neck and the eye. Thoracic bending was also noted to cont ribute in setting the viewing angle, although to a lesser extent. On t he other hand, viewing distance and trunk inclination showed significa nt correlation.