A laser beam to the eye shows humans a color we've never seen before

Just when you think you've seen it all, researchers claim to have developed a way for people to see a color the human eye has previously never seen before. They're calling this new shade 'Olo.'

I want to save you some scrolling by telling you up front that the color has been described by participants in the study as something like a "jaw-dropping," hyper-saturated blue-green.

What that probably doesn't capture is just how mind-blowing it must have been for them to see a whole new color outside the standard human gamut for the first time, when, as far as you can tell, your brain can probably conjure up just about any hue in your mind's eye.

Here's an approximation of what that could look like, going off of an image shared by the researchers with The Guardian.

So how do you see Olo? Well, you'll need a shot of laser blasted at your eye. Just a little shot, really. But first, it's worth understanding how we see regular colors in the first place.

Humans have two types of cells in their eyes to help them see: rods and cones. While the former are tuned for seeing in the dark, cones come in three types that are each sensitive to long (L), medium (M), and short (S) wavelengths of light. When they process a blend of wavelengths of light, we perceive them as different colors.

Now, L cones are largely stimulated by red light, and S cones are stimulated by blue light. There is no natural monochromatic light that exclusively excites the M cones, because their spectral response overlaps with the L and S cones. With this in mind, the researchers looked to stimulate just the M cones with the aim of displaying novel colors beyond the bounded gamut of human vision.

The researchers included ophthalmologists and scientists from the University of California, Berkeley, and the University of Washington. Their technique, dubbed Oz, starts with a mouthful of a process called adaptive optics optical coherence tomography, where they map a section of a participant's retina to pinpoint the M cones.

Next, while you are looking at a target, the Oz system uses infrared light to track the tiny, constant movements your eyes make at a cellular level.

Once the eye movements are tracked, the system calculates exactly how much each individual cone cell needs to be stimulated with light to produce the desired color.

Finally, a technology called adaptive optics scanning light ophthalmoscopy (AOSLO) is used to deliver very short, precise bursts of visible laser light to thousands of M cones, one at a time.

This cell-by-cell control allows for the potential to create novel colors like Olo by stimulating specific cone types in ways that don't occur naturally.

"The whole point is that this is not the color we see, it’s just not," said Austin Roorda, a vision scientist who authored the study that appeared in the journal Science Advances last week. "The color we see is a version of it, but it absolutely pales by comparison with the experience of Olo."

It's interesting to note that this study has polarized experts. Color-vision scientist Kimberly Jameson at the University of California, Irvine, called it an “extraordinary achievement,” while John Barbur from the same field at City St George's, University of London said, "It is not a new color," and described the work as having "limited value."

That last bit remains to be seen. This is the first time researchers have stimulated individual cone cells across a large enough area to alter what a subject perceives through their vision.

The next step for the team is to use learnings from this work to explore whether color blindness can be addressed, and whether regular vision can be augmented further.

Source: Science Advances via Medical Xpress