Improved Stereoacuity Testing with the Judgement of Equal Distances

Abstract

Stereoacuity tests do not usually require the judgement of equal distances. A stereoacuity test which included zero disparity and required equal distance judgements was used to investigate the effect of overall aniseikonia on depth perception thresholds and the disparity of subjective equi­distance ( DSE ). The results of this investigation are reported. The same data were used to determine the effect that a forced choice without the judgement of equal distances would have on test results. Three different ways of responding to a forced choice were simulated by redistributing equal distance respon­ses between left and right nearer responses. These simulations often produced apparently better stereoacuities. From this, it is concluded that equal distance judgements improve the quality of stereo­acuity test results.