A team of researchers has just generated the perception of a new color they have called “Olo”, and that, apparently, had never been seen before. The lucky ones have been five people whom they stimulated laser a specific type of their photoreceptors.
First of all, it is necessary to clarify that the colors “do not exist” as such, since what we perceive in the retina, at the bottom of the eye, is light. There, our photoreceptors (the cones) transform it into nerve impulses and these, once processed, are interpreted by our brain as color. It is equivalent to what we know as the visible spectrum, a very narrow portion of the electromagnetic spectrum.
Specifically, the wavelengths of the light responsible for us to perceive the colors interact with the cones. It is the mixture of that information, depending on what cones are stimulated, allowing our brain to solve the color (or the colors) we are seeing.
Conster of cones
Human beings are trichrome because we have three kinds of cones: those that respond to the longest lengths (L), which we perceive as red; At the middle lengths (m), which we perceive as green, and the shortest (s) we perceive as blue. I mean, we see in RGB (acronym for English red, green, blue“Red-green”).
In total, we have 6 million cones, and chromatic perception depends on how and how many are activated at all times. Each object absorbs a series of wavelengths and reflects others, which will correspond to the color we are seeing. Thanks to all this, humans can distinguish around one million colors. And none is the one who has just discovered.
What researchers asked is what a person would perceive if only one type of cone was activated. To do this they used a device they have called Oz Vision System (thus baptized in honor of the Esmeralda city of L. Frank Baum The Oz Wizard), A laser capable of selecting and stimulating about a thousand photoreceptors of a single modality in isolation, without the involvement of the other two types.
The scientists stimulated with this system only the M cones (those that respond to the wavelengths that we appreciate as green) of a small area of the eye in the five participants in the experiment. These said they had seen a blue-truth color more intense than any other they had perceived before.
A unique experiment
The cones for green cover the middle zone of the visible spectrum, so its stimulation strip flashes with that of the cones for red (l) and with those of blue (s). In the case of these last two, there are certain “natural” conditions in which some wavelengths can stimulate them in isolation, but due to that overlap with the cones L and S, the independent activation of the cones M is not possible in typical light conditions.
Therefore, using this type of laser that can independently isolate and stimulate photoreceptors M was the only way to check if it is possible to generate colors that do not exist in the usual human perception.
The name of the new color is associated with the terminology used in binary code, that is, the combinations of 0 and 1 that are used to represent information in computer science. “OLO” represents the binary number 010: of the three types of cones, as only type M is activated, it is represented as 0 (the S is not stimulated), 1 (the m) and 0 is stimulated (the L is not stimulated).
How can someone know if a color has never seen before?
The subjects described “Olo” as a “greenish blue with unprecedented saturation.” However, chromatic perception has objective components (deficit to distinguish colors, visual problems, etc.) and subjective. A person can infer whether what he is seeing is novel or not by comparison with previous experiences, for example, but that appreciation enters into subjectivity.
To verify that indeed all participants received a completely different color from the already known, chromatic correspondence experiments were carried out, comparing the perception of “Olo” with which they received with a blue -green laser beam, which adjusted saturation by adding white light. The five agreed that, by adding white light to “Olo” – that is, reducing its saturation – the result coincided with the color of the laser. This confirmed that “Olo” is outside the visible spectrum known to the human being.
Anyway, from an objective and scientific perspective, a person cannot know with absolute certainty if a color that he is perceiving has never seen it before, since there is always a subjective component difficult to save.
In addition, we cannot be 100 % safe that someone on this planet, for some anomaly in their cones, has the ability to perceive “Olo” naturally, even if it is not aware of it. Or how can we be sure that a tetrachromata person, capable of identifying up to 100 million shades in our visible spectrum, cannot distinguish “OLO” without the need for microlastic pulses? It is something complicated to demonstrate.
Can we reproduce “Olo” so that we can all see it?
It is impossible to see “Olo” with the naked eye. By its nature you cannot reproduce or digitally. There is no “natural” light stimulation that exclusively activates the cones m of our retina. Although we can find circulating images that say they resemble bluish green color with a very high saturation, that wavelength they represent cannot only activate our cones M.
As for the possible practical applications of Oz Vision,
This tool can be very valuable in basic research to explore still unknown functions of our photoreceptors, since it allows to isolate and study specific groups of these cells in conscious people, something that until now was not possible.
In addition, it could help better understand the mechanisms that give rise to visual diseases in which photoreceptors deteriorate or lose, which would open new ways to prevent or treat them.
The authors also suggest that generating the perception of novel colors in experiments with human subjects could have future applications in the creation of new experiences, enriched and personalized, in visual therapy or, even, in communication and art. Although promising, these applications still seem to be far from becoming come true.
This article was originally published in The Conversation.