摘要
视差是产生体视感觉的主要因素.但视差过大时这种体视感觉也不能存在.这时随着双眼视差的增大从融合为单一像到成复像,而引起体视“崩溃”.本文对正常人和体视欠缺者用心理物理试验方法结合视觉诱发电位(VEP)分析,测量了人眼体视“崩溃”的视差上限阈值.并在改变刺激图形亮度和面积时加以比较.我们的结果表明正常人体视上限阈值,其视差高于2度,在某些情况下这个“崩溃”阈值达到3度.体视欠缺者的“崩溃”阈值约为1.5度.亮度和面积变小会使体视“崩溃”阈值下降,但在这种情况下体视欠缺者的“崩溃”阈值不会下降.可以认为1.5度是人的最低上限阈值·体视存在时VEP的N峰潜伏期约为220—300ms,P_3峰在280—340ms之间.无体视现象(视差为零和过大)这两个峰的潜伏期明显加大.
Disparity is the main cue for forming stereoscopic perception. This stereo- scopic perception will disappear when the disparity is larger than nornal range after the stereoscopic image become doubled. This phenomenon is named stereopsis 'collapse'. The threshold of upper limit of disparity of stereopsis collapse was measured by psychophysical experiment with YEP analysis. Five persons, four normal stereoscopic vision and one abnormal, were as the experimental subjects. Changing the brightness or size of image, the thresholds of upper limit of disparity of stereoscopic collapse were also changed. The results indicated t at the threshold for normal persons is higher than 2 degree, sometimes the collapse threshold reaches to 3 degree. The collapse threshold is about 1.5 degree for persons with poor stereopsis. Thresholds reduce with decreasing of brightness or size of image, but in the same situation the collapse threshold does not reduce for persons who has poor stereopsis.It is considered that 1.5 degree is the lowest threshold of upper limit. The latency of N2 peak of VEP is about 220-300msec.and the latency of P3 peak is aboat 260-340 msec. while the stereopsis exits. The latency of N2 and P3 increase when stereopsis disappears (such as disparity is near zero or larger than normal range).
出处
《生物物理学报》
CAS
CSCD
北大核心
1991年第4期597-602,共6页
Acta Biophysica Sinica
基金
国家自然科学基金
