The effect of length differences between corresponding lines on stereopsis from single and multi-line stimuli

Abstract The amount of depth seen in a random line stereogram composed of orthogonal corresponding lines steadily diminishes as line length is increased. The line length required to destroy stereopsis completely is the same regardless of the disparity incorporated in the stereogram. These results with multi-line stimuli are discussed in connection with previous observations made with single-line stimuli. It is suggested that depth shift effects found with single lines can be explained by supposing that orthogonal line percepts fuse at their endpoints and that as line length is increased this results in an altered retinal disparity of the endpoints and hence a shift in apparent depth. The findings with multi-line stimuli cannot be explained in this simple fashion and require a model of stereopsis which takes into account interactions between elements in complex displays.