Visual illusions
Unfilled flicker
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To do: Use the controls to set the shape of the target and the flickering quickness. To notice: When the box flickers slowly, each flicker is of long duration and the box appears to be filled-in. When it flickers quickly (short duration flicker) it appears to be "unfilled": the center appears to be about the same color as the background. But even in the unfilled condition, the inside of the box is filled from the edges to some small extent, which is why we see a black frame. When the box flickers quickly and is skinny, however, the edges of the box are closer together and it appears filled-in, even though it has short duration flicker. Unfilled Flicker is an illusion in which we can see that it is the edges of stimuli that evoke the strongest neural signals in our brains. |
SOURCE:
"The Role of Spatiotemporal Edges in Visibility and Visual Masking" - Macknik, SL, Martinez-Conde, S and Haglund, MM (2000). Proceedings of the National Academy of Sciences (USA), vol 97(13) pp 7556-7560
Standing Wave of Invisibility
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To do: Use the buttons below the illusion to vary the distance of the masks (outer two bars) from the target (the central bar). This will vary the effect of the masks on the target: the closer the masks the more powerful the effect on the target. Pressing and holding the buttons gives the best results. To notice: As the distance between the mask and the target decreases, so does the visibility of the target. The Standing Wave of Invisibility is an illusion in which the visibility of the central bar in the display above (the target) is decreased by flanking bars (the mask), which flicker in alternation with the target. The illusion shows that a set of masks can render a target perpetually invisible, even though the masks don’t overlap the target in either position or timing. |
SOURCE:
"The Role of Spatiotemporal Edges in Visibility and Visual Masking" - Macknik, SL & Martinez-Conde, S, & Haglund, MM (2000). Proceedings of the National Academy of Sciences (USA), vol 97(13) pp 7556-7560
The Dichoptic Standing Wave
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To do: Wear 3D-glasses that have one red lens and one blue or green lens. Then operate the controls as in the Standing Wave of Invisibility. To get a free pair of 3D anaglyph glasses in the mail, go to Rainbow Symphony's website. Use the buttons above the illusion to vary the distance of the masks (outer two bars) from the target (the central bar). This will vary the effect of the masks on the target: the closer the masks the more powerful the effect on the target. Pressing and holding the gives the best results. To notice: As the distance between the mask and the target decreases, so does the visibility of the target. The Dichoptic Standing Wave is similar to The Standing Wave of Invisibility in that it is an illusion in which the visibility of the central bar in the display above (the target) is decreased by flanking bars (the mask), which flicker in alternation with the target. The illusion shows that a set of masks can render a target perpetually invisible, even though the masks and target are in separate eyes. |
The Stoper-Mansfield Effect
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To do: Press the button above to turn on a circular mask within the box. Press it again to turn the mask off. To notice: With the mask on, the black box is inhibited from completely filling-in (notice the white aura around the circular mask). Without the mask, the box appears fully filled-in. The Stoper-Mansfield Effect is an illusion in which we can visualize inhibitory activity within our own brains. |
SOURCES:
"The Role of Spatiotemporal Edges in Visibility and Visual Masking" - Macknik, SL, Martinez-Conde, S and Haglund, MM (2000). Proceedings of the National Academy of Sciences (USA), vol 97(13) pp 7556-7560
"Brightness perception and filling-in" - Paradiso, MA and Nakayama, K (1991). Vision Research Vol. 31 pp.1221-1236.
"Metacontrast and paracontrast suppression of a contourless area" - Stoper, AE and Mansfield, JG (1978). Vision Research, vol 18 pp 1669-1674