Stereogram Animation Drawing Magic Eye, Animation, landscape, grass, cartoon png 600x580px 930.86KB.Training Learning Stick figure Management, 3d figures and toothache stereogram, furniture, presentation, public Relations png 1530x1600px 1.1MB.white light, Fountain stereogram, white, atmosphere, microsoft Azure png 1134x1134px 223.83KB.“Neither one can make it down the street alone, but if they lean up against each other, they stay upright.”Ĭopyright 1995 Discover Magazine. “The regions may be like two drunks,” says Ramachandran. That might explain the sensation some people have when looking at autostereograms: when they start to see the outline of a hidden object, the 3-D illusion suddenly kicks in. Ramachandran thinks the object-recognition and depth-perception regions of the brain may work in tandem, bouncing signals back and forth. The people saw the illusory triangle floating in 3-D–even though the gaps prevented them from making the point-by-point comparison of left and right images that Julesz thought was essential to depth perception. Ramachandran created left-eye and right-eye versions of this illusion and had people look at them through a stereoscope. Even though there are gaps in the sides of the triangle, you see it whole because your brain fills in the gaps. The illusion consisted of three circles, each of which had a wedge cut out of it, arranged so the wedges formed the corners of an imaginary triangle. Vilayanur Ramachandran of the University of California at San Diego has shown as much by making a stereogram out of an optical illusion. The pattern elements then fuse into left-eye and right-eye images of a single hidden object, which appears to be floating in space.Īlthough Bela Julesz can be considered the grandfather of the autostereogram craze, it turns out he wasn’t entirely right about how the brain perceives 3-D objects.
They’ve been shifted in such a way that when you look at the pattern cross-eyed (or in some cases look “through” it), the neighboring strips overlap. They consist of repeating vertical strips, like wallpaper, in which the pattern elements–random dots or something more complicated–have been shifted to one side, a la Julesz. Object recognition must come later.Īutostereograms, which can be viewed without a stereoscope, were invented in 1979 by psychologist Christopher Tyler. He and others concluded that depth perception is one of the first things the brain extracts from the visual signal, by comparing the left-eye and right-eye images dot by dot. But when Julesz put both of them into a stereoscope, people saw a dot-covered square floating in front of a similar background. If you looked at either field alone, you couldn’t see the square. In each field he drew an imaginary square around some of the dots and shifted them slightly to one side, filling in the blank gaps with more dots. In 1960, however, Bela Julesz, a psychologist now at Rutgers University, challenged that idea with a new kind of stereogram made of two identical fields of randomly scattered dots. The first stereograms were both a commercial smash and a neurological breakthrough: scientists realized that depth perception arises from the way the brain compares signals from the two eyes, which see an object from slightly different angles.įor over a century researchers assumed that the brain needed to recognize the signals as an object before it could compute the object’s 3-D shape. Victorian researchers discovered that they could create a 3-D illusion if they took photographs of an object with two cameras a few inches apart and had a person look at the images through a stereoscope, which allows each eye to see just one of the photos. The mystery has its roots in a previous 3-D craze, back in the nineteenth century. What the slack-jawed millions may not have realized, though, as they stared at books and posters, is that they were experiencing an enduring mystery of neurology: When the brain perceives a 3-D object, which comes first, the object or the 3-D? In 1994, America became addicted to autostereograms–those swatches of psychedelic wallpaper that dissolve into three-dimensional images when you stare at them cross-eyed long enough.
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