Which visual phenomenon occurs when two colors appear similar under certain lighting but different under another?

The phenomenon of two colors appearing similar under certain lighting conditions but different under others is known as metamerism. Metamerism occurs because the human visual system perceives colors based on the way different light sources interact with the pigments in the observed colors.

When a color is viewed under one lighting condition, its appearance can be affected by the spectrum of light present. If the same color is viewed under a different light source, such as fluorescent versus incandescent, the wavelengths of light that are reflected can change, leading to a different perception of that color. This is due to the way the brain interprets colors based on the wavelengths of light that reach the retina and the comparative quality of surrounding colors.

This phenomenon highlights how subjective color perception can be and emphasizes the importance of consistent lighting in color assessments. The ability to recognize and differentiate colors accurately can be influenced significantly by the environmental lighting, thus illustrating the concept of metamerism vividly in practical scenarios.