What’s weirder, it was only green and red that worked. “Colors near pure blue and pure yellow, which had little red or green content, produced weak aftereffects,” the study noted.. As far as we can tell, there isn’t a good explanation for why red and green are so good at producing the effect compared to others.
As for the grating thing? Well, that might be due to neurons in your visual cortex responding more strongly to their “preferred orientation and spatial frequency,” according to another study. It even suggested a rather interesting theory, that the JPEG image format used “plaid-like” (chequered) patterns, which are basically two gratings overlaid on each other.
Then if you look at this image, it should appear red or green in parts, or even pinkish. Android Mouse/Wikimedia
