For the first time, scientists have identified specific colour-sensing cells in the human eye and turned them on. And somewhat surprisingly, many of them don’t help us to perceive colour, according to a report in Science Advances.
The team found 273 cone cells in the eyes of two male subjects and employed flashes of light then asked the men to describe what they saw. While some cone cells relayed colours, others simply relayed whiteness. This result suggests that the mind handles information about colour in a different manner than it does brightness and form.
The human retina (the back of the eye, think of it as the screen for a movie projector) is filled with rods and cones. These are light-sensitive cells. Rods are particularly helpful with night vision and perceive light, not colour. They are a sort of sensor in other words and have to be receptive to very small amounts of light. In the opposite condition, bright lights are handled by cones.
M-cones process green light, while L-cones handle reds and yellows and S-cones blue. The wavelengths of these colours are different as well: reds and yellows are longer while blues are short.
When M-cones and L-cones are activated alone most of them perceive white although a smaller number process red and green. The results were consistent and the cone cells showed the same results on different days.
These cones help the eye to process information about black and white or colours. The brain uses this information to process borders and where things begin or end and fills in with the correct colours and shades.
The cones that deal with white, in other words, allow for fine detail and gradation which allow us to perceive opportunity and danger, first of all, but also fine art and things that engage us in other ways.