Why We Can't Stop Seeing Zigzags in This Freaky Optical Illusion

[Judi Lynn]

By Brandon Specktor, Senior Writer | December 12, 2017 02:01pm ET

- click for image -

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An example of the curvature blindness illusion. What do you see in the middle: wavy lines, angular lines, or both?
Credit: Kohske Takahashi

Who would win in a fight: the part of the brain that likes to see curves or the part that prefers corners?

This conflict underlies a new kind of optical illusion, dubbed the "curvature blindness illusion" in a new paper published in the November-December issue of the journal i-Perception.

Kohske Takahashi, an associate professor of experimental psychology at Japan's Chukyo University, showed a small sample of students the image below and asked them a simple question: What do you see in the gray, middle section of this picture — curved lines, angled lines or both? [The Most Amazing Optical Illusions (And How They Work)]

If you see alternating rows of wavy and zigzagging lines (like all study participants did), you're both right and wrong. The truth is, every line in this image is an identical, wavy shape. And yet, our brains reliably see sharp-cornered zigzags stitched across the middle section of the image. The reason this illusion works so well is unclear, but Takahashi offers a few hypotheses in his paper.

More:
https://www.livescience.com/61176-curvature-blindness-illusion.html?utm_source=notification

[eppur_se_muova]

1. When the two colors meet at a point of sharp curvature, our eyes seem to want to read that as a fold

but when they meet in a less curved section, nothing happens. When the background is either lighter or darker than both colors, it seems our eyes (brains, really) don't seem to attribute the different shadings to lighting, so ... not a fold.

Interesting to explore this some more.

[Igel]

2. Gentle curves.

Not angles. But not as curvy as elsewhere.

Peripheral vision shows they're angular, but when I look at a spot, they're gently curved.