Binocular fixation is achieved by rotating the eyes, but this process also transforms the pattern of image disparities. This effect is problematic for biological visual systems, in which stereopsis is based on simple, short-range mechanisms. It is argued here that the problem should be addressed in two ways; firstly by an appropriate representation of disparity, and secondly by modelling the typical pattern of image correspondences. It is shown that the average spatial structure of the disparity field can be estimated, over a series of binocular fixations. An algorithm based on this idea is tested on natural images. Finally, it is shown how the average pattern of disparities could help to put the images into binocular correspondence.