Why certain color combinations drive your eyeballs crazy

Why do websites in certain colors seem to rip out your eyeballs? It's not just the tacky color combination. It's the fact that your brain gets hijacked to see these colors in 3D. Some appear to recede, while some seem to float forward. It's called chromostereopsis, and it's why designers avoid some colors like the plague.

We're always using color to make inferences about an objects depth and position. Light and shade subtly change the color of objects, and let us know which parts of them are advancing or retreating. We notice that color can fade when it becomes very distant, and that at some distances different colors seem to blend together. Color is one of the cues that we use to understand the physical world.

Sometimes those cues, and that association of color with depth, can deceive us. Pair one color with another and, to our eyes, it will look like one color is floating in front of, or behind, the other. This is called chromostereopsis, and works with things like Rothko paintings. It does not work with things like graphic design.

Why certain color combinations drive your eyeballs crazyS

The color combinations differ. Putting together red, blue, and black, will give people the illusion that the red is advancing, the blue retreating, and the black hanging between the two. Blue will also seem to retreat when paired with yellow. Green will usually appear to float on top of red. These positions can flip depending on perception. Some people, when surveyed, found that blue advanced and red retreated. There is nearly always a 3D component to the colors. Almost no one sees simply one color next to anther color on a flat piece of paper or a flat computer screen. The colors have a spatial relationship to each other.

No one has entirely pinned down the reason for this spatial color shift. Some believe that it is due to the lens of the eye refracting different colors slightly differently in space - the way a prism bends different colors of light to different angles. Others believe it's in part because of the Crawford-Stiles effect, which shows that light passing along the edge of the pupil will be seen less effectively than light passing through the center of the pupil. People hold their eyes in different positions when they study objects, and these positions can affect the perceived depth of the colors. Studies, which have shown that chromostereopsis differs greatly depending on pupil size, do back this theory up. But we still haven't figured out all the mechanics of the illusion. For now, it's just important to never pair green, red, and blue together on a page and expect people to read it.

Via NCBI, Ritsumei, and Science Direct.