Anybody who's taken psychedelic drugs has likely seen this color already. Overlapping sensitivity of the cone cells doesn't matter when the image is generated without light. Psychedelic visuals are full of impossibly saturated colors.

You can also approximate this effect by tiring out some of the cone cells by staring at a bright area of saturated color, then looking at a different color. See:

https://en.wikipedia.org/wiki/Impossible_color#Chimerical_co...

I was going to suggest perhaps auras — people who see these (associated with migraines).

So basically, the sensitivity curves of the receptors in the eye overlap ( https://commons.m.wikimedia.org/wiki/File:Cone-fundamentals-... ) so a signal can’t excite a single type of receptor, but they did it by using a focused laser to exclusively target the one type of receptor?

Right!

This is fascinating. I didn't realize there are so few cone cells, that you can step through literally *all* of them with a digital controller.

- "These laser microdoses are delivered at a rate of 10⁵ per second to a population of 10³ cones[...] individually fiber-coupled acousto-optic modulator that can modulate laser intensity up to 50 MHz[...] This laser spot is scanned in a raster pattern over a 0.9° square field of view using orthogonally oriented resonant and galvo mirrors, with a frame resolution of 512 × 256 pixels and a frame rate of 60 Hz..."

https://www.science.org/doi/10.1126/sciadv.adu1052

About 90 millions rods vs 6 millions cones. Sometimes I'm surprised we can even see detail at all. Though it certainly helps that they're not uniformly distributed; most cones are in the macula, around the middle of the back of the eye. Still, it's not a lot.

And within the macula, the red and green are generally towards the centre and the blue are generally towards the edge. This helps prevent the red shift problem photographs with high contrast changes sometimes get.

This is the basis of chroma subsampling (like the common 4:2:0, 2 chroma samples for every 8 luma samples) in encoded video.

They didn’t literally step through all of them though (only a patch “about twice the size of a full moon”), and I’m not sure if they even stimulated all M cones within that patch.

Ah, mea culpa then. The other commenter says there's 6 million cone cells, which is a much larger number than the 1,000 in this experiment.

A comparison of interest then is the area of that patch relative to the fovea.

Its be neat to incorporate this into a AR headset. They could potentially map non-visual wavelengths to new colors (or is just the one possible?). Probably never going to be practical due to the precision it requires, but imagine seeing actual colors with IR/XRAY/UV overlayed on to in a new color!

Reminds me of the Cylon in Battlestar Galactica who hated his creators for giving him senses limited to human limits when machines could do so much more.

Someone should at the least make a Sci Fi movie with this idea as a plot device.

This is a bit like fuzzing the visual system with invalid input. ;)

This reminds me of horror fiction like Lovecraft's Color Out of Space[1] and Neill Blomkamp's short Zygote (2017)[2][3]

[1] https://en.wikipedia.org/wiki/The_Colour_Out_of_Space

[2] https://www.imdb.com/pt/title/tt7078780/

[3] https://www.youtube.com/watch?v=pKWB-MVJ4sQ

Octarine?

I think they'd have to hit a different part of the CNS for that. :)

I came here just for this. Terry Pratchett would have a field day…

Original paper here - https://news.ycombinator.com/item?id=43734141

My knowledge of color vision is hand-wavey. This isn't artificially simulated (or stimulated) tetrachromacy, right?

No, it's still within the span of the ordinary three color receptor types. It's just the ratios within those three are outside of the usual, possible ratios.

There's a Wikipedia article about the topic,

https://en.wikipedia.org/wiki/Impossible_color

The Wikipedia article also includes instructions on how to see these colors, so "never seen before" is a bit strong.

Technically, the technique they are using may give you a slightly different color than the Wikipedia pictures would lead you to. Depleting one color and then looking at the other color would still technically have the original rod firing at some fraction of its recharge rate rather than zero. But that would be the difference between RGB(252, 0, 0) and RGB(254, 0, 0) and not something like those versus RGB(10, 0, 0). It produces nearly the same color.

I'm actually surprised the article doesn't mention it. That the journalist doesn't know about this is not a huge surprise but I'd kind of expect the researchers to know that there is in fact a way to see at least flashes of these out-of-gamut colors for normal people with no special equipment. It's just a static picture that would easily fit into the article.

Cool, but I wish it said how the participants subjectively would have described the experience.

This is always weird. Like the environment is basically that which can be interpreted by sense. So then what is base reality and does it even exist?

They saw a hooloovoo -- a super-intelligent shade of blue!