The easiest way is to use the principles of conditioning. Pair a stimulus with a certain color light, then start flashing up different colored lights. If the organism is cued to the stimulus by multiple colors of lights, it means that they can't really distinguish between them.

That's how we tested when kids lose the ability to distinguish certain phonemes.

They give them a miniature color blind print that has those numbers in them that are hidden if you are color blind.

For anyone wondering why they would need to see polarized light: I actually looked into this a few months ago!

Other animals that are trying to blend in with the environment often use countershading appear less conspicuous. The problem with this is that this method can't replicate the polarization of the light behind them, making them stand out if you can see that sort of thing. ((Sunlight in the ocean is always polarized based on the direction of the sun (look up fresnel equations for s and p polarized light))). Even transparent creatures will interrupt the polarization in some way, so this is a very useful skill to have.

"Spiders can detect danger coming their way with an early-warning system called eyes."

Really fantastic book. I did have some notes though. Firstly, if honeybees have such low dpi vision, how can they see each other dance? I assume it's because they're experiencing the dance some other way, but how? (Also it's hella dark in there, isn't it?)

He says many times that humanity's umwelt is dominated by sight, but I very much disagree. To lose my hearing or sense of touch would make me feel quite blind, as I use them to perceive things outside my cone of vision constantly. Being in deep water is unnerving for this reason, because I can't "see" what's around me, and I have this whole new area below that I can't hear either. So I have to wonder whether other people feel the way he does or whether my usage is more unique.

He really blew my mind when describing exafference and reafference because these things are reliant on a sense of self in the first place, which means that even the worm in his example must have some form of ego.

You mean light red?

Shrimp has more color receptors because he doesn’t have enough neurons to run trichromacy, so he sees in EGA.

love this. nice job :)

Oh man.

12 year old me waiting for hours to rip mp3s from cds always wondered about this.

Like why isn't it already compressed?

The answer is that storage was available but processing wasn't. Amaze.

Ha! I read the following Science new article just today about how Purple Only Exists In Our Brains. It's written for a younger audience (I think), but it lays out how our sight works, and how our brains trick us into seeing purple (a red-blue colour, as opposed to violet).

Poor shrimpos, no purple for them, I bet.

It’s amazing and crazy to think, too, that the “theater” our brains create is an equilibrium point of laziness (to save energy) and usefulness (to help survival). So, surely, there are things we are just unable to see. But also, probably, there are different things that get mapped to the same things in the “theater.” I’m just speculating though but it makes sense.

Color me appointed, at least we're not missing out on fresh new colors!

Ruined my day tbh

That's silly thinking. Everyone knows birds aren't real, so they're just late-stage planes created by engineers forced to follow certain constraints.

Did a shit job of it too, got the wings all flapping around like a bunch of idiots.

Thanks I was gonna check

Still one of today’s lucky 10K!