Try this: Gazing straight ahead (as you will no doubt at some point be urged to do if you start hanging out with Trevor and Ryan Oakes for any length of time these days), extend your right arm straight out to your side, perpendicular to your gaze, your hand in a fist, your thumb pointing upward, starting out from behind your ear and now slowly arcing the arm forward. (The Oakes boys, that is: identical twins, just past twenty-five years old, both artists, now living in New York City but before that from out of West Virginia.) At first you won’t see the upraised thumb, of course, but presently, there it will appear, at the periphery of your vision. Keep moving your arm forward until the thumb’s extended out there straight in front of your face at the center of your gaze; now with your left hand extended, thumb up, hand off the arcing transit, as it were, continuing along until eventually that thumb disappears behind your other ear. The thing is (as the Twins will explain with earnest enthusiasm and at quite considerable length), there was only a short part of that transit where you were seeing the thumbs with both eyes and hence with any sort of depth perception. Through most of the rest of the experiment, your nose was blocking the vision from out of one, and then the other, eye. And yet your brain, your visual cortex, was weaving the scene into one continuous, undifferentiated experience. (“Pretty cool, no?” By now the Twins will have veritably lit up with boyish enthusiasm.)
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