The video discusses the evolution of human eyes, focusing on how they have adapted to be visually evident to others, which helps in discerning where someone's focus or attention lies. Few concepts like the contrast of the white of the eye with the colored iris and black pupil are believed to have evolved to clarify intent and make eye movements more detectable. This evolutionary trait might have been pivotal for survival because it helped identify intentions and emotions, therefore avoiding misunderstandings and facilitating mating opportunities.

Additionally, the relationship between perception, color vision, and emotion perception is explored. Emotional cues like blushing and flushing are discussed in the context of signaling shame or anger, and how these cues are perceived and interpreted in social interactions. These cues are considered almost involuntary, signaling honesty in emotions, which enhances social interaction by allowing for trustful engagements.

Please remember to turn on the CC button to view the subtitles.

Key Vocabularies and Common Phrases:

1. salient [ˈseɪliənt] - (adjective) - Strikingly noticeable or prominent. - Synonyms: (prominent, conspicuous, noticeable)

The hypothesis being that anyone in our evolutionary history whose eyes weren't salient was.

2. fecundity [fɪˈkʌndɪti] - (noun) - The ability to produce abundant offspring or new growth; fertility. - Synonyms: (fertility, fruitfulness, productivity)

...and cues of fecundity. But tell me about the emotional cues that are associated with differences in color.

3. blushes [blʌʃɪz] - (noun) - A reddening of the face as a result of embarrassment or shame. - Synonyms: (reddening, flush, glow)

With spectral skin signaling is blushes. Right. And blanches and flushes.

4. frugivore [ˈfruːdʒɪˌvɔːr] - (noun) - An animal that predominantly feeds on fruit. - Synonyms: (fruit-eater, herbivore, plant-eater)

Does the theory that trichromate vision evolved at least partly, or perhaps in the main as a aid to emotion detection, contradict the frugivore theory?

5. empath [ˈɛmpæθ] - (noun) - Someone with the ability to understand and share the feelings of another. - Synonyms: (sensitive, compassionate, understanding person)

And there's all kinds of things where we, we, we, we leverage our color vision, which is peculiarly for empath kind of health senses

6. stereoscopy [ˌstɛriˈɒskəpi] - (noun) - A technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. - Synonyms: (3D view, depth perception, binocular vision)

And so there's been multiple kinds of. One is stereoscopy a better stereoscopy?

7. occlusion [əˈkluːʒən] - (noun) - The blockage or closure of a passage or opening. - Synonyms: (blockage, obstruction, closure)

Yeah, occlusions in front of other things.

8. interpupillary [ˌɪntərˈpjuːpɪlərɪ] - (adjective) - Relating to the distance between the pupils of the eyes. - Synonyms: (pupil distance, optical separation)

So for objects that are less, objects that are not as big as this interpupillary distance, the separation between my eyes, then when you're an animal in that, with those kinds of eyes, in a forest with leaves that are typically smaller than that, you actually get, I call it X ray, you actually can see.

9. stereopsis [ˌstɛriˈɒpsɪs] - (noun) - The perception of depth produced by the reception in the brain of visual stimuli from both eyes in combination. - Synonyms: (depth perception, binocular vision, 3D vision)

stereoscopy loses always. All of these other ones trump. They win if there's.

10. pruning [ˈpruːnɪŋ] - (noun) - The act of trimming or cutting away unnecessary parts, used metaphorically to describe evolutionary changes or adaptations. - Synonyms: (trimming, cutting, reduction)

Whether it's pruning fingers, still probably in the Wikipedia page it says it's a side effect of osmosis or some bull crap.

Humans Effectively Have X-Ray Vision - Mark Changizi

So one of the things that I've read. I don't know if you believe that this is true, but, you know, because everything turns out to be debatable among scientists, just like everyone else. But I've read that one of the things that shaped the evolution of our eyes is their shaping to be maximally visually evident to perceivers. Right. We're unbelievably good at determining exactly where someone's eyes are pointed. So even if someone is sitting across the room from you, you can tell if they're looking at your eyes or at the tip of your nose, which is such a tiny fraction of. Of movement at the eye level or a fraction of angle that it's almost amazing. It's amazing that you can detect it at all. And that we have the white background and the colored iris and the black pupil, partly because that maximizes immediate the degree to which our eyes are salient. The hypothesis being that anyone in our evolutionary history whose eyes weren't salient was. salient was someone whose intentions were very difficult to determine and was much more likely to be misunderstood, say, and killed in consequence, or much less likely to find a mate. And so our faces have evolved, at least at the level of our perception of the eyes of others, to ensure that we can understand intent. And we do that by inferring attention by looking at eye gaze.

And you're making a strong case in your work for the relationship between perception, color vision and emotion perception. So we talked a little bit about cues of health that might be associated with skin coloration and cues of fecundity. But tell me about the emotional cues that are associated with differences in color. So, you know, the first thing I think people think about with. With spectral skin signaling is blushes. Right. And blanches and flushes. But that's really just the beginning. You know, this barely touches the surface. So you can imagine someone's angry and they can get red face, which is very different from when somebody blushes and they get with embarrassment. And people. Actually, if I'm in front of a stage and something happens that's slightly embarrassing, and the audience is over there and I'm looking this way, you actually blush more on the side that's facing the audience, your body. Oh, is that right? Yeah. This is known. This is a Drummond. Wow. That's a very specific response. Right. So these are strong arguments that these are signals, not just automatic side effects of, you know, some kind of implicit side effect with no purpose. Well, that's so complex too, eh? Because it opens up the question like first of all, not everybody blushes. And the issue is, well, what does the blush signify? And it signifies something like self conscious shame. And then the question is, well, why would you want to signal self conscious shame to people? I mean, because it's a shameful signal. But it does indicate that you're the sort of. One of the things that might indicate is that you're the sort of person who can't get away with what exactly. Violating the social norm, something like that. Right. And it's, and it's an honest signal because it's out of your control. So.

Yeah, right, honest, honest signal just in this context is, doesn't. Is a sort of a technical term of art. So we mean by honest signal that you have no control over it and when. And it wears its meaning on its sleeve in some sense. Right, right. So yeah, that's right. It's a signal of your intent beneath your conscious awareness. Laughter, genuine laughter seems to be a signal like that too. And there's some evidence that genuine smiles are like that too. Right. Because if you smile falsely, your eyes don't smile. Although I think you can train yourself to do that. But generally speaking, yeah, it's hard if someone is manipulating with a smile, they don't do it the same way they do when they smile spontaneously. And so those rapid onset implicit emotional displays are a signal about our genuine motivations. And if those signals are obvious, it's in principle easier for people to read us and therefore in principle easier for us for them to engage in trusting negotiations with us. Right, because we wear our heart on our sleeve. That's right.

And so, I mean, other predictions that come out of this, by the way, it should be the case that if this is true, then the primates with color vision, as opposed to the primates that didn't have a 3, 3, 3 color vision. The primates with color vision should have more naked spots. They show bare faces. And in fact, when you look, the primates with, with color vision are the ones with naked faces. They often have naked rumps, you know, naked genitalia, which, because all of these things are signaling. The ones without color vision are furry face, like your typical bunny rabbit. Typical dog nakedness and color vision, three color vision are opposite sides of the same point.

Okay, okay, okay. Does the theory that trichromate vision evolved at least partly, or perhaps in the main as a aid to emotion detection, contradict the frugivore theory? Like, is it possible that color vision also gave us an edge, at least in some environments, with regards to the detection of higher quality food sources, it's, it's certainly possible, but it wouldn't have driven, there's no reason to think that fruit would have driven those particular wavelength sensitivities of the middle and long wave wavelength sensitive cones, particularly given that they're so close together. Right. So that, that's the crucial issue.

Yeah. And there's all kinds of things where we, we, we, we leverage our color vision, which is peculiarly for empath kind of health senses. But we obviously use it for lots of things probably in nature beyond that and in culture use all over the place. But that doesn't mean that that doesn't amount to an explanation for what Dr. The problem, I guess that people have with evolutionary, functional evolutionary explanations for the purpose of any given human attribute is that there's no reason ever to assume that any given attribute is singular in its function. It's sort of like asking what the hand can do. What's the hand for? Well, you know, the hand is for a lot of things. What's the, is there a cardinal purpose to the hand? That's a hard question to ask, but there's no reason to assume that evolution wouldn't operate so that a given biological phenomenon. Well, here, here, here would be other than multi purpose. Right. Well, so the, everything might be multi purpose but the odds of there being two competing or multiple competing decidata that are determining the design that they're close to one another are going to be typically fairly rare. Typically one of them might be ten times more important than that. Right. You know, or a thousand times more important. Usually. In my experience it turns out that one of these is the principal drivers. It can explain first order, even second order properties of the thing. And yeah, there can be other third or fourth order stuff, but that's, that's slight, mostly irrelevant so you can get away with explaining.

So for example, another, another one why we have forward facing eyes. Standard story. And the fun thing of all of these, these, these explanations, whether it's pruning fingers, still probably in the Wikipedia page it says it's a side effect of osmosis or some bull crap. Right. It's just, it's still there to this day, these old narratives. And then for forward facing eyes it's going to, it's always has something to be about. Predators want forward facing eyes. Well, except that every fish is a predator eating a smaller fish. All the birds are birds. They all have sideways facing eyes. By our standards they're all sideways facing eyes. Even, even all the carnivores the paradigmatic, you know, mammalian meat eaters, predators have sideways facing eyes relative to us. I mean they still have forward facing eyes in terms of the big picture effects. So there's a lot of variability and forward facing eye ness across the mammals. And the question is, why is there this variability?

And so there's been multiple kinds of. One is stereoscopy a better stereoscopy? But you even get stereoscopy in a bunny rabbit. Bunny rabbit has a very thin binocular field and it can see stereoscopy within a thin binocular field. But it also gets the benefit of seeing everything you can see directly behind it, below it, above it. So you've got this full panoramic vision. Whereas we've chosen to lose a lot half of our visual field or you know, a lot of our visual field just to have better stereoscopy up in front now. So one of the bad sorts of.

You have these two currencies like, you know, the standard arguments. Oh, I've got this great wide stereoscopy field of better 3D vision up front at the expense of losing everything. How do you balance those things? How is that an argument that I would want more of apples to have while getting less adverbs in the back? Not even obviously comparable things that I can trade off.

So my argument is, first of all, stereoscopy is not the least important 3D sense. We have all of these. There's many, many three dimensional senses. One is just what kinds of objects they are, how far down towards the, the, towards the horizon are they, how they overlap things. Yeah, occlusions in front of other things. If I just do this with one, even with one eye, I'm getting amazing, much better than stereoscopy all these things when you, when you do. If you're perception psychologists who create stimuli with that have competing cues of two different kinds and they say which ones trump. stereoscopy loses always. All of these other ones trump. They win if there's.

Oh, I see. So that's a good way of testing what's the most cardinal element of the. Oh yeah. And so none of the stereoscopy always lose. And if you've played first person shooter video games, yeah, you have both eyes open but you're being fed one image on screen. And these things are so immersive, you never are confused as to where the guys are that you're shooting. Right. They're always really unambiguously in one particular spot. Yet you're a Cyclops. Right. So it had occurred to me back then, I Said I don't think it has anything to do with stereoscopy whatsoever. And it turns out it's all about one currency.

This is again to this idea of why, why aren't there three, two or three or more equivalent kinds of functions that are all competing? And then it's just some ugly mess. And it's not a good design hypothesis at all. It's sort of these sort of ugly kludge that happens to. It's almost never a kludge. And so in this case, the reason that we have forward facing eyes and the more forward facing they are is to see better and clutter. And so what I mean by that, animals that evolved with leaves all over the place, when there's leaves, if your eyes are more widely separated than the clutter leaves, let's say. So for example, if you, if you, you've played this game, if you just.

If I hold my finger up in front of you, it's very thin and I look at you, but not my finger, I see two copies unless I've got a dominant eye. But for those of you who don't have a dominant eye, you'll see two copies of your finger and each will be semi transparent. Right? Right now, right. You're see, you know what you can see through it, right? So what essentially what one eye is being blocked with the other eye seeing the world beyond that. And so your brain has evolved to just create two copies of it. And you're not confused, like, oh my God, I've got two figures. No, you know, what's going on. It's just you have this perception that combines them and creates semi transparency so that you can see beyond it.

Now even my whole hand, I'm almost missing nothing, even with my whole hand in front of me. You know, there's a little bit of a core in the middle, but I'm capturing most of it. So for objects that are less, objects that are not as big as this interpupillary distance, the separation between my eyes, then when you're an animal in that, with those kinds of eyes, in a forest with leaves that are typically smaller than that, you actually get, I call it X ray, you actually can see.

It's probabilistic summation. You actually can see much, much more of the environment beyond than when you're a cyclops. So and in fact I noticed this playing video Games back 20 something years ago when I would be, you know, because you're a cyclops and you're hiding in bushes and I'd be trying to snipe people. And then when you're in a bush, you can't see anything. Of course, these are fake bushes. I get it. You can't see anything because you're just looking at the real life. You're in a bush, you pretty much see the entire world outside of it. You know, peek from outside of your bush. So you had to keep shaking to get different shots. And someone shoots you because they see you wiggling in the bush.

In real life, you're designed to be in these cluttery environments and to see perfectly well beyond that without having to move too. Without having to move. And yes, you're losing what's behind you, but then you can start calculating how much of the environment can I see? If I'm a forward facing animal with this X ray ability, that is my eyes are bigger than the leaves versus a rabbit, let's say effectively, who has a full panoramic view. Yeah, he can see entirely behind him, but he can't. You can actually then calculate how much of the world outwards can you see? He's actually. I can see up to.

If you think about it two dimensionally, I can see up to 1, 2, 3, 3 and a half times better than him. If you think about it as a two dimensional grid, but in fact it's more of a three dimensional grid, then you have to sort of think about spheres, sphere packing problem. And so I can see only the front half of my little sphere. But if the little. The world is sort of built out of these spheres, of these little. Surrounded by lots of clutter, I can see the six spheres in front of me fully and I can't see beyond that. And only half of mines, but I can see now six and a half times more of the.

There's like simple models that you can build of simple models of forested kinds of environments where you can show that now you can see really almost an order of magnitude more.

EDUCATION, SCIENCE, INNOVATION, COLOR VISION, HUMAN EVOLUTION, VISUAL PERCEPTION, JORDAN B PETERSON