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by gumby 1600 days ago
Humans don’t really use stereopsis beyond the reach of their arms (which makes sense if you think about it). Beyond that we use semantic cues, which is why we can also understand pictures.

Sadly most research in this area went out of fashion 30+ years ago.
2 comments
tbabb 1600 days ago
> Humans don’t really use stereopsis beyond the reach of their arms

This is outright false. A person with acute vision can perceive stereopsis out to 1/4 mile. Trivially, 3D movies are projected onto screens which are 10m away.

> which is why we can also understand pictures

We don't drive using pictures.

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AnimalMuppet 1600 days ago
> Humans don’t really use stereopsis beyond the reach of their arms (which makes sense if you think about it).

But of course we do. It's how we throw rocks and hit what we aim at. It's how we catch things. It's how we walk around anywhere that has obstacles. We use it beyond the reach of our arms really frequently.

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oh_sigh 1600 days ago
I can still throw a rock fairly accurately with one eye closed. I can catch pretty much perfectly with one eye closed. I can walk around without hitting anything with one eye closed.
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Sohcahtoa82 1600 days ago
The point was that you don't need stereopsis to do that.

Basically, could you do it with one eye closed? Without stereopsis, tasks involving close-up things are harder, but farther away things are not.

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AnimalMuppet 1600 days ago
Depends. If I'm hunting with a bow or a throwing stick, I'd bet stereopsis is pretty important. Do I need it? Maybe not, but I'll be more accurate with it.

If I'm running through the woods, trying to escape from a bear, stereopsis is pretty useful, because dodging trees while at a dead run is life or death.

I don't do either of those, but some of my ancestors probably did. But I play sports. I may be able to catch a ball with one eye. Getting myself to where the ball is going? I couldn't do that as well with only one eye.

So: Do I need stereopsis? No. Did the human race? Yes, it was a competitive advantage to have.

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tbabb 1600 days ago
> I play sports. I may be able to catch a ball with one eye

I would love to see a sports game where one team can use both eyes, and the other team only has one eye uncovered. I imagine it'd be downright funny.

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