ROYGBIV...O? A Closer Look at the Newly Discovered Color ‘Olo’ and How We Can See It

From an early age, we are taught the colors through the rainbow. In preschool, we go over each primary color and begin to add on new ones as we age. However, regardless of age, we are only taught about the colors that we can see, despite there being a world beyond that of other colors that can only be artificially created.

All light falls somewhere on the spectrum known as the electromagnetic spectrum. Since light behaves as both a wave and a particle, we can measure its wavelength, or the distance between two peaks of the wave. This ranges from wider wavelengths of radio waves and microwaves to smaller wavelengths of x-rays and gamma rays. Humans can only see the part of the spectrum known as visible light, which encompasses the whole rainbow of colors from wider wavelengths of red at around 700 nanometers to smaller wavelengths of violet at around 400 nanometers. 

Our eyes pick up on light using special cells known as photoreceptors. These cells, when interacting with light at specific wavelengths, send signals to our brain through our nervous system. Cells called neurons send electrical pulses to one another, and these pulses travel from the cells of our eye to those of our brain. When the brain reads these signals, it can tell where the light came from based on the location of the photoreceptors in the eye. For example, if light comes in from the right side, photoreceptors on the left side will receive it.

Different photoreceptors pick up different levels and types of light. There are two kinds of photoreceptors: rods and cones. Rods pick up on lower levels of light and are primarily used for night vision. They are less sensitive to color but more sensitive to light itself. This is why our night vision seems to be monochromatic—only in black and white. Around 95 percent of the photoreceptors in our eyes are rods.

On the other hand, cones pick up brighter light and are more sensitive to color. Most people have three types of cones: a short cone for picking up shorter wavelengths of light (blue), a medium cone for picking up medium wavelengths of light (green-adjacent), and a long cone for picking up long wavelengths of light (red). Based on the combination of these cones that are activated by the light coming from an object, we are able to discern the perceived color of something.

Nearly all objects we see emit a combination of different colors of light, giving them distinct hues. However, to further study color reception, scientists at the University of California, Berkeley, designed and tested a technology called Oz to isolate specific wavelengths of light and target certain, single types of cones within the eye. Using a laser that emitted only the specific wavelengths picked up by the medium (M), cones, they were able to isolate that cone and create a color that is the result of the activation of only that cone—a color that humans would never be able to see naturally from ambient light reflecting off of other objects around us. To do this, they first mapped the retinas of each participant in order to get the exact location of the cones they aimed to stimulate and then identified the specific M wavelength of 543 nanometers—a wavelength that was deemed the “most” green and matched the medium cones—to create the correct hue of green for the laser.

Participants describe the new color, which they have dubbed “Olo,” as an intensely bright teal. According to the study, when asked to represent the color Olo as a commonly visible color, they had to desaturate the teal color with white light to make it comparable. This means that Olo is outside of the normal gamut of human vision since its saturation is unnaturally high.

This study is unique because it created the color as an image in the eye rather than as an afterimage. An afterimage is the visual remnant formed when someone stares at a specific color for too long—exhausting the photoreceptors for that color—and then closes their eyes or looks away. This will briefly create a color that is the complete opposite of the original color and often one that is impossible to see in natural light. Some examples of these “forbidden colors” are an impossibly bright hyperbolic orange, impossibly deep stygian blue, and self-luminous red.

The applications of this study are numerous: with the current use of virtual reality, this study is a fantastic example of how your eye can be manipulated in order to see a specific color, which can be used to further enhance virtual reality simulations. Additionally, Oz technology can be used to study rare eye conditions such as tetrachromacy—a condition that results in a person having four primary colors rather than three due to the presence of four types of cones. Since Oz can stimulate one specific cone at a time, it can assist in any study relating to color perception, possibly even helping scientists find new ways around color blindness. Color blindness is often caused by the malfunctioning of proteins called opsins in the cones—for example, red-green color blindness comes from the inability to distinguish red and green because of the malfunctioning of their proteins. As a result of this, with Oz technology, scientists can work on targeting specific cones over others and observe which ones are the most effective.

Overall, this new color, Olo, opens up a new world of scientific studies into the workings of color perception. Scientists might be able to create two other “impossible” colors similar to Olo by stimulating the other two cones on their own—or perhaps even rods. So, in the future, be on the lookout for new colors!