Mark Changizi

All the birds are predators. They all have sideways-facing eyes. By our standards, they're all sideways-facing eyes. Even all the carnivores, the paradigmatic 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 of things. So there's a lot of variability in forward-facing eyeness across the mammals.

And the question is, why is there this variability? And so there's been multiple kinds of... One is stereoscopy, 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. It can see directly behind it, below it, above it.

And the question is, why is there this variability? And so there's been multiple kinds of... One is stereoscopy, 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. It can see directly behind it, below it, above it.

And the question is, why is there this variability? And so there's been multiple kinds of... One is stereoscopy, 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. It can see directly behind it, below it, above it.

So you've got this full panoramic vision, whereas we've chosen to lose... Right, a lot. Half of our visual field, or 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 the standard argument is, oh, I've got this great wide stereoscopy field of better 3D vision up front at the expense of losing everything.

So you've got this full panoramic vision, whereas we've chosen to lose... Right, a lot. Half of our visual field, or 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 the standard argument is, oh, I've got this great wide stereoscopy field of better 3D vision up front at the expense of losing everything.

So you've got this full panoramic vision, whereas we've chosen to lose... Right, a lot. Half of our visual field, or 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 the standard argument is, 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 of apples to have while getting less adverbs in the back and not even obviously comparable things that I can trade off. So my argument was like, first of all, stereoscopy is not, it's the least important 3D sense. We have all of these, there's many, many three-dimensional senses.

How do you balance those things? How is that an argument that I would want more of of apples to have while getting less adverbs in the back and not even obviously comparable things that I can trade off. So my argument was like, first of all, stereoscopy is not, it's the least important 3D sense. We have all of these, there's many, many three-dimensional senses.

How do you balance those things? How is that an argument that I would want more of of apples to have while getting less adverbs in the back and not even obviously comparable things that I can trade off. So my argument was like, first of all, stereoscopy is not, it's 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 horizon, Are they? How they overlap? Things, yeah, occlusions in front of other things. If I just do this with one eye, even with one eye, I'm getting amazing. Right, right. Much better than stereoscopy.

One is just what kinds of objects they are, how far down towards the horizon, Are they? How they overlap? Things, yeah, occlusions in front of other things. If I just do this with one eye, even with one eye, I'm getting amazing. Right, right. Much better than stereoscopy.

One is just what kinds of objects they are, how far down towards the horizon, Are they? How they overlap? Things, yeah, occlusions in front of other things. If I just do this with one eye, even with one eye, I'm getting amazing. Right, right. Much better than stereoscopy.

All of these things, if you're a perception psychologist who creates stimuli that have competing cues of two different kinds, and they say, which one's Trump? Stereoscopy loses always. All of these other ones trump. They win if there's competing. Oh, yeah.

All of these things, if you're a perception psychologist who creates stimuli that have competing cues of two different kinds, and they say, which one's Trump? Stereoscopy loses always. All of these other ones trump. They win if there's competing. Oh, yeah.

All of these things, if you're a perception psychologist who creates stimuli that have competing cues of two different kinds, and they say, which one's Trump? Stereoscopy loses always. All of these other ones trump. They win if there's competing. Oh, yeah.

And so none of the... Stereoscopy always loses. And if you've played first-person shooter video games, you're... 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?

And so none of the... Stereoscopy always loses. And if you've played first-person shooter video games, you're... 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?

And so none of the... Stereoscopy always loses. And if you've played first-person shooter video games, you're... 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.