We found that 30 % of non-stereoanomalous observers, aged 19 to 25 years old, did not use disparity in making depth judgments in 3D-graphic environments. However, several questionnaires indicate that the use of disparity can be learned unconsciously, suggesting that poor stereopsis can be improved by appropriate training procedures.

We investigated the individual differences in the use of binocular disparity and proposed a method for improving stereopsis in observers who do not perceive depth from disparity in 3D-graphic environments. In Experiment 1, non-stereoanomalous observers, aged 19-25 years, were asked to roughly evaluate the depth of 3D-graphcial stimuli containing binocular disparity and shading. The results of Experiment 1 showed 30% of the observers were pseudo-stereoanomaly who perceived depth only from shading. In Experiment 2, 60% of the pseudo-stereoanomalous observers were able to use disparity when they had to assess the depth concretely. In Experiment 3, all of the observers who participated in Experiment 2 learned to use the disparity information when retasked with roughly estimating again. These results suggest that quite a few people have difficulty in experiencing rich depth perception in current 3D-graphic environments. However, appropriate training procedures would improve their use of disparity information over the long term.