Abstract
One sees floors more frequently than ceilings, and looks up at vertical objects such as persons or walls more frequently than looks down at them. This is true especially for young children in the critical period of stereopsis. With these conditions objects in the upper visual field are farther than the fixation, and objects in the lower are nearer than it. It may be assumed that the stereoscopic system is more adept at processing uncrossed disparities in the upper and crossed in the lower. The current study examines depth perception in each visual field with crossed and uncrossed disparities. In the experiment, a fixation and a test target were presented for 0.8s on a stereoscope. The fixation was right in front of the observer and the test was on the median plane; the test appeared at upper or lower visual field with a crossed or uncrossed disparity. The eccentricity of the test target was 1.5, 3, or 6 degree. The given disparity was 0, 3.6, or 7.2 arcmin at 1.5 degree eccentricity, 0, 7.2 or 14.4 arcmin at 3 degree, and 0, 10.8, 14.4, or 21.6 arcmin at 6 degree. The task of the subject was to report the apparent depth of the test target: 3AFC from far, near, or zero. 33 subjects participated. 15 of these subjects gave no anomalous signs. Five indicated defection of uncrossed or crossed disparity detection (Richards, 1970). Two seemed to be stereoblind or depth-reversal (Gillam, 1967). The other 11 could not perceive depth from crossed disparities in the upper and/or uncrossed in the lower. These results support our expectation.
Meeting abstract presented at VSS 2013