If you’re a pet owner, you might know that dogs don’t perceive color very well. It’s a bit of an exaggeration to say that they’re color-blind or that they only see in black and white, but they’re certainly not as good at perceiving fine hue variations as their human companions.
In fact, humans are actually pretty talented at perceiving color. No matter where you are while you’re reading this, you can likely look up from your screen and see dozens or hundreds of different hues, particularly if you’re within eyeshot of a window. But you probably don’t give much thought to how you’re able to achieve this impressive feat, or what has to happen in your eyes, optic nerves, and brain to make it possible.
How Do We See Color?
The Harvard Gazette reported that university researchers located the part of the human brain responsible for processing and recognizing color in the late 1990s. The precise location was actually a bit of a surprise. Similar tests on monkeys two decades earlier revealed the tree-climbing primates’ color centers to be in an adjacent, but different, brain region.
The process of seeing and interpreting color happens in a literal split-second. Our retinas have millions of light-sensitive structures called cones. For color-perception purposes, there are three main types of cone, each designed to perceive a particular wavelength range corresponding with one of the three primary colors (each primary color is a tighter wavelength range at the corresponding structure’s peak sensitivity).
When exposed to light, the cones communicate with retinal ganglion cells (nerve cells) via electrical signals. The ganglia interpret these signals, essentially coding for color, and then forward them to the brain along the optic nerve. After passing through the lateral geniculate nucleus in the brain’s thalamus region, the signals reach the primary visual cortex, where the spatial relationships between the colors (among other important pieces of higher-level information without which our visual experience would be very different) are assigned and preserved. This is how we “remember” color, and how it suffuses our emotional lives.
Birds Do It Better
Lest you get overly prideful about your brain’s ability to recognize and remember color, remember that humans aren’t the only animals capable of perceiving a stunning range of hues. In fact, we’re not even close to being the best at recognizing, seeing, and processing color. That honor goes to the birds — literally.
As an order, birds are far better at perceiving color than mammals, among which humans are better than most. Some birds are frighteningly good at seeing color — their eyes and brains have actually unlocked a portion of the near-visible light spectrum (part of the ultraviolet spectrum, in human terms) off-limits to mammals, such that they are able to see four primary colors.
The takeaway is clear: While the human brain is most definitely amazing, it’s best not to get cocky. Overconfidence is for the birds.