Other Depth Cues
2. Color Effects
This can actually be a disruptive effect. The fluids in our eyes refract different wavelengths of light differently. Given two objects whose size, shape, and distance from an observer are the same, if they have different colors, our vision processing system may lead us to believe incorrectly that one is farther away than the other. Specifically, light with short wavelengths (e.g., blue) appear to be closer to the eye than objects with long (e.g., red) wavelengths. Also bright objects appear to be closer to the eye than dark ones. In the image on the left, for example, all four spheres are the same size and distance from the eye, but the darker ones appear to be farther away.
