Purpose. To examine oculomotor responses to targets presented within a non-immersive stereoscopic (3D) display where accommodation and vergence cues to depth conflict. Methods. A liquid crystal frame sequential shuttering system was used to create the computer generated 3D imagery. The imagery comprised eight visual targets arranged radially at a number of different disparities (0, +0.5, +1, +2, +3, +4, -0.5, -1.0, -2.0, -3.0 and -4.0 deg) around a central fixation point lying in the plane of the display. The targets were equal in size (1, 2, or 3 deg) and equidistant (10 deg) from the centre. The subject's (n=4) task was to look at a target for 3 sec when an arrow indicating the target location appeared. The subjects were instructed to attempt to keep the target clear and single. Head position was fixed and binocular vertical and horizontal eye movements were recorded with a differential IR system. Results. Vergence tended to change appropriately, especially for targets along the horizontal, for both crossed and uncrossed disparities of up to 2 deg; however, for some subjects large inappropriate vergence changes occurred when the target lay out of the plane of the display. These individual differences appeared to be related to the subject's AC/A ratio. Little or no effect of target size on vergence level was found. Conclusions. These data suggest that the accommodation vergence mismatch inherent in this type of display may in some cases interfere with eye movements, a finding important when considering the use of such virtual 3D displays.
Neary, C. (1996). The effect of 3D virtual images on eye movement control. Investigative Ophthalmology & Visual Science, 36, 784