Human eyes are separated by about 50–75 mm between pupils (Dodgson 2004). Therefore, each eye views the world in a slightly different way. The difference between these images is referred to as binocular disparity and provides important information that is not available from either image alone. The amount of disparity depends on the difference in the distance of the two objects and the distance of the fixation point. The greater the disparity, or distance, between the two images, the closer the object is to the fixation point. Binocular disparity is a necessary condition for stereopsis, which is the sense of depth the brain generates from information obtained by the left and right eye. This helps us to see the world in three dimensions, rather than two dimensions.
The idea that binocular disparity contributes to depth perception was first described by Sir Charles Wheatstone in the nineteenth century after he invented the stereoscope, a device used for observing pictures in three...
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- Goncalves, N. R., Ban, H., Sanchez-Panchuelo, R. M., Francis, S. T., Schluppeck, D., & Welchman, A. E. (2015). 7 tesla FMRI reveals systematic functional organization for binocular disparity in dorsal visual cortex. The Journal of Neuroscience, 35(7), 3056–3072.PubMedPubMedCentralCrossRefGoogle Scholar