For the majority of the population, the world is a rich visual palette that gives depth and texture to the things we see around us. The panoramic explosion of color in a a fireworks display, the muted tones at a formal gathering, or the riot of hues on display at a Mardi Gras celebration, these are all examples of situations in which color is such an integral part of the experience that one cannot imagine anything different. So as far as colors are concerned, we can already see all there is to see… right?
Paranormal ocular powers are a staple of science fiction literature, such as X-ray vision, heat (infrared) vision, and telescopic vision. The fascination with such abilities is a long-standing and ubiquitous pillar indicative of a wild imagination- how many kids sent away good money for those X-ray specs that invariably failed to live up to their advertised ability? That said, there are some amazing visual abilities that exist in our world, though most of them are not found in humans.
As any dog or cat owner can attest, when looking for your pet in the middle of the night, waving that flashlight around can reveal a startling sight- a pair of brilliantly lit eyes calmly regarding you from the cover of darkness. This effect, observed in a large proportion of animals, is due to the tapetum lucidum, a retroreflective structure that intensifies available light through constructive interference. This lowers the minimum threshold of vision, allowing excellent sight in dimmer light. Humans lack a tapetum lucidum, thus our ability to see in the dark is limited by what light is already detectable by our photoreceptors. Thus, some animals can see with astounding clarity under conditions that hinder human sight.
Another interesting natural phenomena is tetrachromacy. What human beings see normally is based on our trichromatic vision: namely, the ability to process short, medium and long wavelengths of light that correspond (roughly) to blue, green, and yellow-green portions of the visible spectrum. What gives rise to the diverse range of colors that we can perceive is how the brain processes the information it receives from all three channels. In tetrachromatic vision however, four wavelengths can be detected, allowing organisms such as birds and insects to detect light outside the (human) visible spectrum. The evolutionary advantage that such vision would grant animals is related primarily to mating and hunting behaviors, e.g. – an insect detecting differences in UV reflection of one flower versus another, or a raptor able to see the spoor of a mouse on the ground.
Compared to such amazing natural visual abilities in the animal kingdom, human sight is thus fairly limited. Or is it? In 2010, a woman who demonstrated the visual acuity of what a hypothetical human tetrachromat would be able to perceive was discovered by Dr. Gabriele Jordan and colleagues. In their work, they originally tested individuals that demonstrated what researchers termed “anomalous trichromacy”, and later concluded that one of their test subjects demonstrated “behavioral tetrachromacy”. The immediate results of Dr. Jordan’s work suggests that for some humans, their field of vision is functionally broadened. How such individuals would perceive the world is fascinating, though having a tetrachromat attempt to describe what or how they see the world to a trichromat is analogous to a trichromat trying to do the same to a partially color-blind dichromat.
The range of natural abilities in the world is stunning, and some humans may possess a rare combination of genetics that grant them skills and traits that set them apart from their peers. This recent discovery of a woman who sees the surrounding world in ways that the majority of the population cannot suggests that individuals with unique and fascinating abilities exist among us, yet continue to remain quietly unrecognized.
So keep your eyes open- there is much more to be seen in the world than is immediately apparent.