Abstract: Psychophysical experiment is the main method in the study of stereopsis. YEP was first used in the study of stereopsis since the 1970's with much re- sult. As YEP is very complicated the results were not satisfactory. In this paper we compared psychophysical experiments and VEPs in the research of stereopsis. The results showed that the first positive peak of VEP related to brightness of the stimulus; latence of N2 and P3 are useful for determining stereopsis; the latence of N2 is about 240 to 280ms for stereopsis and latence of N2 for none stereopsis is about 290 to 310ms; the latence of P3 is about 280 to 310ms for stereopsis and the latence of P3 is about 340 to 360ms for none stereopsis; the coefficient of coherence of VEP between stereopsis and none stereopsis is below 0.1; the density of power spectrum for stereopsis has a peak of around 8hz; the results with forced choice in psychophysical expe- riments is fairly reliable; the latence of N2 and P3 for stereopsis shows regu- larity while disparity was changed.

Key words: VEP, psychophysics, stereopsis, power spectrum