The attenuation of activity when a wide-angle shot was shown after a tighter picture indicates, Intraub says, "the brain is going, 'ho-hum, I've seen that before.'" In the PPA there was decreased activity in every scenario, except when a close-up followed a wide-shot. An equivalent activation was measured when the second picture appeared in every scenario-except when a close-up followed a wide-angle shot. In the RSC there was a spike of electrical activity when the first photo was flashed. Eighteen subjects were shown two successive photos of scenes, such as a fire hydrant on a lawn, in one of four pairings: close-up then wide-shot, wide-angle then close-up, wide followed by wide or two close-ups in a row. The team focused on two brain regions known to be associated with scene-specific perception: the parahippocampal area (PPA), an area in the bottom half of the brain between the two cerebral hemispheres, and the retrosplenial cortex (RSC) in the outermost layer of the cerebrum. In the current study, Intraub teamed up with psychologist Marvin Chun's lab at Yale University to see, via functional magnetic resonance imaging (fMRI), if the behavior she had observed was actually taking place in the brain. Basically, Intraub says, it appears that "the brain is already planning around the edges," and this may be a way to "help integrate successive eye fixations." Interestingly, if people are shown the same picture and then a wide-angle version of it-with the bike a little smaller (because more of the fence is in the shot)-they may mistake the second photo as being the same as the first. At the time she found that when people are shown the same picture twice-say a bicycle in front of a white fence-within several milliseconds, they will mistake the second picture as a close-up of the bike and not the same portrayal. In 1989 Intraub co-authored a paper that first characterized boundary extension. "The world surrounds you, but you only have those two eyeballs right in front or your head" with which to take it in, says Helene Intraub, a psychologist at the University of Delaware and a co-author of a new study in Neuron on visual processing. The answer could lie in a wrinkle of image processing called "boundary extension," whereby the brain represents a scene not only by inputted information, such as a picture, but also by what it extrapolates is beyond the picture's borders. So, with all this frantic movement (not to mention temporary blindness), how is our brain able to piece together a complete, detailed, uninterrupted picture of the world? During this shift in attention vision is suppressed and a patch of momentary blindness occurs. Previous research determined that eyeballs fix their gaze on a particular spot for one third to a couple of seconds in between glances they dart around for up to 50 milliseconds. Whether we are drinking in a scene, picture or vista, our eyeballs dart about wildly to take in different features of the view.
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