Light strikes an object. Some of it is absorbed, the rest reflected. The reflected wavelengths, if they chance upon an eye, travel to the rod and cone cells of the retina. Short-wavelength cones register blues, medium cones greens, and long cones reds. But because the medium and long cones are similar, a light source will likely activate both. There is no light on Earth that can excite only the medium cones.
At least until this past April. Researchers at Berkeley have developed Oz, a high-precision laser system that can selectively stimulate M cone cells. Test subjects described the result as a wavering block of color, slightly off-center and entirely new. Researcher and electrical engineering and computer science Professor Ren Ng characterized it as “the tealest teal,” while his colleague, doctoral student James Fong, named the never-seen-before hue “olo.”
By probing how the brain interprets new signals, the Oz system may one day allow scientists to expand the visual palette through a kind of “virtual cone” that would act in addition to the original three. These theoretical colors wouldn’t be comparable to teal or any other familiar hues. Ng suggests the frontier of color perception lies in getting the brain to process entirely new inputs. Here, description becomes nearly impossible.
“With olo, people could have a picture in their mind that fairly represents that,” he said. “For the kind of colors that we’re working on now, the best analogy I could give is seeing red for the first time. How do you describe that to someone?”
For now, olo is visible only with specialized equipment and has only been experienced by a handful of people. But its existence suggests that the brain may be capable of processing a wider spectrum of colors than the world naturally offers.
