It’s always been fun to discuss whether or not people perceive colors in the same way. That can be tricky enough when dealing with individuals with normal color perception, but those who have various degrees of color blindness have a limited range. But what about those who have a greater range?
The human eye is packed with millions of cone-shaped cells that allow for color to be perceived. For those with normal vision, the three types of cones allow vision of about one million distinctive colors. Some animal species including certain birds, insects, fish, and reptiles, have a fourth type of cone cell that extends color perception into the UV range. Though evolution has mostly scrubbed that fourth cone from the mammalian lineage, there is evidence that a small group of humans may have a genetic variant that allows for tetrachromacy. Concetta Antico, an Australian artist, was confirmed to be a tetrachromat in 2012.
Antico, who now lives in California, is an impressionist. Rather than creating works of art that are as realistic as possible, impressionism gives her the freedom to add splashes of color as dynamic parts of her compositions. This mirrors her description of her color vision: Even if an object is monochromatic, she claims to see a range of other colors existing in a mosaic.
The genes responsible for red and green cone cells are located on the X-chromosome. An individual genetic variation responsible for tetrachromacy would need two copies in order for the trait to be expressed. As such, it is assumed that because men only have one X-chromosome, only women are capable of being tetrachromats. On the flip side, this is also why men are more likely to be colorblind than women. Men don’t have a backup in case they receive a faulty copy of those genes. Women, on the other hand, would need to inherit two copies to code for color blindness.
Even though tetrachromats’ eyes may be able to interpret a wider range of the electromagnetic spectrum, most vision really happens in the brain. The eye picks up information (ie. light) and sends it back to the brain for processing. The actual processing system between tetrachromats and those with normal trichromatic vision is fundamentally the same, though there is evidence that focused training could allow for perception to be expanded. The fact that Antico trained as an artist may have contributed to her expanded color perception. Of course, the condition in humans is so rare and understudied, it’s hard to know the full potential without identifying and studying more tetrachromats.
Testing for tetrachromacy can be a bit difficult, as most tests are based on trichromatic vision. Genetic analysis revealed Antico does have the genetic variations that allow for a fourth type of cone cell. Though this mutation has given her an incredible gift of expanded color perception, it has left her daughter colorblind.
Antico has been working closely with a team of researchers investigating human tetrachromacy. By understanding more about the condition and how the neural pathways involved with color perception can be trained, they might be able to discover a way for others to boost the amount of colors they see as well.
Concetta Antico’s condition and artwork can be discovered in further detail on her website.
[Header image credited to Concetta Antico]
[Hat tip: Popular Science]