When looking at the image above, what do you see? Wavy lines or zigzag lines? I see both, and according to psychologist Kohske Takahashi, who discovered this optical illusion in 2017, seeing zigzag lines means I have "curvature blindness."
In other words, there aren't really any zigzag lines, only curvy ones. The good news is, I'm not alone – most people see zigzag lines.
For a good explanation of the "curvature blindness illusion," as it's called, and the science behind it, go to Science Alert.
Image from video below, which shows nothing but this image. (If you dare open it, you might want to turn off the sound, which is akin to scratching nails across a chalkboard.)