We see colors with our brain, not with our eyes. Colors don’t really correspond to any one particular thing in the physical world that the eye could simply detect. Under natural viewing conditions, the color that we perceive a surface to be depends on the whole spectrum of light wavelengths it reflects, and on the context of the surface in the overall visual scene.
The perceived colors of surfaces stay the same, even when lighting conditions change drastically. An apple that looks red in natural sunlight still looks red when viewed indoors, under incandescent light. Seeing colors must depend on a complex analysis in the brain of the light wavelengths that the eye detects.
In 2020 a team of American researchers announced major findings about how the brain allows us to perceive colors. They showed human subjects colored pinwheels while monitoring the activity of their brain using magnetoencephalography. This technique reveals brain activity by detecting tiny magnetic fields generated by electrically active brain cells. By mathematical analysis of the pattern of brain activity they detected, the researchers could deduce what colors their subjects saw. They studied how much brain patterns for different colors differed from one another.The researchers discovered that brain patterns for warm colors, such as red, orange, and yellow are more different from one another than for cool colors such as green and blue. This may explain why people are better at distinguishing warm colors than cool colors, and why, across cultures, people have more names for warm colors than cool colors. Neuroscientists hope that such methods will allow us to learn much more about how color perception works.