Breaking down psycho-physical functions: Eyesight

Judging__Eagle · Post by **Judging__Eagle** » Tue Jul 07, 2009 2:52 am

So, Eyesight.

Mantis Crabs (Also known as Mantis Shrimp, they are a type of stomatopod) get the best. As far as I have learned at least.

Humans get (in order of what we notice first):

Tonal (1 Photon minimum)*

It should be noted that the Photon is calibrated to average human eyesight. Other creatures could have better tonal visual acuity than humans do.

Many animals do see better than humans in terms of Tonal depth. A deer can get along better in the dusk/dark than a human can, because they have more surface area, and are almost soley devoted to tonal perception (Deer, and most prey animals do not have colour vision, they instead have really wide, or really good black and white vision).

Colour (I think that it's around 6 billion hues (and shades?) 9 sounds much higher than I think that I can see; I'm pretty sure that 1 billion versions of green is the upper limit of what my eyes can see likewise with combinations of the three primay and three tertiary colours).

However, many animals don't, and some humans are partially, or completely colour blind.

Motion, the human eye has a framerate of about 30 frames per second (FPS). Things that move faster than that aren't captured well, and at that point, the next thing that is noticed is....

Outline (shape, not having things look blurry, so the distance that you have to keep a book from your eyes is part of this type of vision, too close, and it's blurry, too far, and it's the same. Better vision gives a wider range of focus on outlines, and you can need correction if you have a negative outline focus.

There's more to it than that, but those are the basics.

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This was just a mental exercise, I've got these ideas for what sort of things are involved in different processes; such as what is the nature of memory, and how do we mentally absorb or retreive things? I really haven't gotten to writing them down before, but I've meant to.

CatharzGodfoot · Post by **CatharzGodfoot** » Tue Jul 07, 2009 4:10 pm

Damn, the mantis shrimp are pretty amazing. As if supercavitating wasn't good enough...
Geckos have full-color night vision (with full 4D, as opposed to stupid mammal vision).

"Outlines" aren't a simple part of vision; they're actually an involved part of visual processing both in the retina and the brain. Figuring out what constitutes a meaningful outline is a very difficult task, which is why photo-editing programs are so awful at it. A number of interesting optical illusions center around the perception of outlines, especially moving ones. I can't find the demo right now, but there's a neat one that shows how the 'pinhole effect' caused by the breaking-down of edges into individual angled lines by early visual processing leads to uncertainty about the direction that a shape is moving in.

Koumei · Post by **Koumei** » Tue Jul 07, 2009 4:58 pm

I recall QI mentioning that pigeons have such crazy good FPS for their eyesight that any movie would look (to them) like a very boring slideshow, with ages between slides.

This explains why they wait until the last conceivable minute (by our standards) to move away from oncoming vehicles, and also explains why they never go to the cinema.

Though it should also be noted that they could only watch G (or whatever everyone else calls "Everybody can watch this" movies) films, which probably also plays a part.

Ice9 · Post by **Ice9** » Sun Jul 19, 2009 8:05 pm

Look up Mantis Shrimp ... that's just ridiculous! They seem like a powergamed character in the "Animal" RPG.

PhoneLobster · Post by **PhoneLobster** » Sun Jul 19, 2009 9:48 pm

There is always that fish that can see through it's own head.

Psychic Robot · Post by **Psychic Robot** » Sun Jul 19, 2009 11:02 pm

That's astounding. What a remarkable creature.

PhoneLobster · Post by **PhoneLobster** » Sun Jul 19, 2009 11:34 pm

It's boring compared to the weird ass critters it is alleged to steal food from. The siphonophores.