When we visualize something, does our brain create one image or two, as in one for each eye?

People tend to think of the two eyes as separately operating video cameras that are sending parallel signals to the brain (more specifically: the occipital cortex). It may seem as if there are two little "vision gnomes" sitting next to each other at twin TV monitors comparing the images at the back of the head.

Actually, the images from each eye are being broken down into their component parts almost immediately upon leaving the back of the eye through the optic nerves. When these various visual elements reach the occipital cortex, they are re-assembled into one coherent virtual image. This single virtual image is then error-corrected and edited by the "Adobe Photoshop" of our brain and "projected" out onto the world we see. This is why we can function effortlessly even though the eyes see somewhat different things and "up-side down" on the retina.

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic