Bored? Here, try this color vision game.
How’d it go? If it went poorly, don’t let the fact that you’re more mole than hawk get you down. It doesn’t necessarily mean you’re color blind. This particular eye test isn’t exactly rigorously clinical. It’s also a better test of color blindness and sensitivity than it is of color vision. Still, it does lead us into an interesting topic: what is color vision? And why do some people seem more sensitive to color than others?
Color vision is the ability to distinguish different wavelengths or frequencies of light by perceiving them as colors. This ability comes courtesy of cones – tiny, light sensitive cells clustered at the back of our eyes- and rods.
When light enters the eye, it stimulates the cones. However, in low-light situations, rods are stimulated instead of the cones. This provides us with predominantly black-and-white night vision. There are three varieties of these cells in human eyes, each more sensitive to a given range of light frequencies.
Cones stimulated by relatively high-frequency light would largely be responsible for our perception of violet. Violet rests at the high-frequency end of the visible spectrum. Cones stimulated by lower frequencies would pitch in more to our ability to see red.
These three varieties interact endlessly, giving rise to the incredible variety of color that we’re capable of seeing. There’s plenty of debate over whether we all see color the same way. But, most humans have the same basic hardware. It includes three different types of color-sensitive cells that feed information about light to our brains.
Humans vs. Animals
This range of three makes humans “trichromats.” While we might think our color vision’s great, it’s quite lousy compared to the rest of the animal kingdom. Granted, we are doing well for mammals. Most of our furry relatives are “dichromats” and only have two types cones, like dogs.
However, that’s where our color perceiving advantages end. Many insects have vision at least on par with our own. Bees, for example, are trichromats, but perceive higher-frequency light than we do. They see ultraviolet better than red, giving them the ability to accurately perceive potential feeding sites.
Reptiles, birds, and fish tend to be a cut or two above us, as many are tetrachromats or even higher. The current record holder for color vision is a shrimp. Mantis shrimp have 12 distinct types of receptors. They might not work identically to our own, but they represent color vision on an entirely different level of complexity.
Differences Among Humans
Even within our species, there’s plenty of variety. The one that you probably know most about is color blindness, a relatively common visual disorder. There are several types of human color-blindness. The most common are various forms of functional dichromatism. This occurs when an individual’s eye either doesn’t have a given type of cone cell. Or, it has one cone variety that doesn’t function normally.
The result is generally an insensitivity to a given range of light. Red-green color blindness, the most widespread form, makes it difficult for individuals to distinguish colors in the green-yellow-red range. Red hues will also be sharply dimmed, which can even make telling purple from blue difficult. Red-green color blindness can even cause you to have a rough time picking up on red lights while driving. Although, most will develop various compensatory methods to work around this problem.
While dichromats are the most abundant departure from the rule of three that you’ll find, there are also very rare monochromats. These are creatures who can only perceive one shade and effectively have total color blindness. Then there’s – intriguingly – tetrachromats.
The latter group is still a somewhat poorly understood one. Genetic quirks mean that it’s possible for some women to have four simultaneously functioning types of cone cells. Indeed, in the past couple of years, researchers have identified women who do seem to have this extra visual boost.
However, whether this would, say, help someone on the color vision test above is up in the air. One identified tetrachromat could verify three different colored lights in a dark room. To the trichromat participants around her, the three lights all looked like the same color. Researchers have found that her extra cone species seem to react to light in the red-orange-yellow range. But, aren’t entirely sure how or if that even affects her color vision on a practical level.
How About the Rest of Us?
Finally, we get down to variety between trichromats.
The first difference you’re going to find is straight out of the battle of the sexes. Women have a genetically finer eye for color. A study from the Medical College of Wisconsin found that each of the three cones in trichromats’ eyes can detect around 100 color variations. However, women seem to be able to see exponentially more hues than men. The reason for this? Genes for certain color pigments, like in green and red cones, are found in the X chromosomes.
Males are born with an X chromosome from their mother and a Y chromosome from their father. Females are born with an X chromosome from the mother and an X from their father. This gives women the genetic lead over men for having more genes for color pigments. According to the Wisconsin study, some women can be born with red cones in each chromosome. Thus, enabling them to have even further superior vision.
However, just because you’re born with certain chromosomes and genes doesn’t protect you from color blindness.
Poor color vision can also be caused by a wide range of diseases and injuries. Glaucoma, cataracts, sickle-cell anemia, some pharmaceuticals, and alcoholism can all cause a reduction of color sensitivity. In fact, anything that causes widespread disruption to normal vision is going to somewhat disrupt color vision.
If you bombed on the color vision test, there’s no need to panic. Just turning up your screen’s brightness could probably help. If you do find yourself having increasing difficulty distinguishing colors though, it may be time to head in for an eye exam. After consulting your eye doctor, test your color vision again and keep an eye out for any improvements.