DISTANCE IN STEREOSCOPIC VISION . THREE-POINT PROBLEM

If the function relating the horizontal disparity between two points and the ratio of their perceived egocentric distances has any form other than exponential, then the distance ratio between two points will be influenced by the presence and position of a third point. Five experiments are reported in which this dependence is shown to exist and is measured as a function of the position of the third point. The functions obtained are inconsistent with several possible explanations of the effect, but are consistent with the hypothesis that the perceived distance ratio of two points is jointly determined by the positions of all the points in the configuration. © 1969.