Open thread, Apr. 24 - Apr. 30, 2017

gilch

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If it's worth saying, but not worth its own post, then it goes here.

Notes for future OT posters:

1. Please add the 'open_thread' tag.

2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)

3. Open Threads should start on Monday, and end on Sunday.

4. Unflag the two options "Notify me of new top level comments on this article" and "Make this post available under..." before submitting.

I really would prefer to the ability to see IR and UV, but in the meantime this is interesting. Sample:

...we designed a wearable passive multispectral device that uses two distinct transmission filters, one for each eye, to enhance the user's ability to perceive spectral information. We fabricated and tested a design that "splits" the response of the short-wavelength cone of individuals with typical trichromatic vision, effectively simulating the presence of four distinct cone types between the two eyes ("tetrachromacy"). Users of this device were able to differentiate metamers (distinct spectra that resolve to the same perceived color in typical observers) without apparent adverse effects to vision

See the paper I linked in my other comment.

4gilch1y

Eight years later, but we're finally approaching the technical capability to perform my proposed experiment to elicit tetrachromacy in a human trichromat through eye tracking and targeting a subset of retinal cells: https://www.science.org/doi/10.1126/sciadv.adu1052#sec-3 See the DISCUSSION section proposing further experiments.

4gilch9y

I'm also interested in what expanded color vision would be like, but it looks like that paper was describing one of the obvious approaches I'd already thought of. I didn't read the whole paper, but from the abstract, it looks analogous to one of the widely-used treatments for color blindness, namely a single red-tinted contact lens. Many other vertebrates are tetrachromats. Mammals are unusual for being more color-blind. The loss of two types of cone cells is thought to be due to the nocturnal phase of our evolution when dinosaurs ruled the earth. Primates have since evolved a third kind again. Birds never went through this phase and are still tetrachromats. A gene-therapy experiment gave color vision to color-blind monkeys. This approach could theoretically produce a fourth type of cone cell as well, but could they then distinguish more colors? Some women may be natural tetrachromats, due to a mutation in a photopigment gene in one X chromosome, but not the other. It's not clear if the tetrachromat ability of certain women is due to ancestral neural pathways from when we were tetrachromats, but given the random way gene therapy works in the monkey's cells, it seems likely that neuroplasticity is enough. Given consistent "pixels" that react preferentially to certain colors, the brain learns to perceive them as colors. Thus, I believe it's likely that the human brain could learn to perceive a color gamut built from even five or more primary colors, given proper inputs. The fact that sensory substitution works suggests a non-invasive approach. If you could track and target the eye well enough for a display to consistently change the color sensitivity of a scattered subset of retinal cells, it's likely you could use it to train your brain to not only distinguish new colors, but to perceive new color qualia.