<p>If you had two objects with words on them, one very large font and one very small font.</p>
<p>The large font object is further away from you than the small font object, but you could see the detail on them equally the same as they appear identical in size to you due to the scale of the objects.</p>
<p>How then does the brain know the difference? How do the eyes know a difference?</p>
<p>They say to look at distant objects to rest your eyes from the computer, but couldn't you just look at smaller font and trick the brain into thinking its looking at a large object far away?</p>
<p>Since we don't consciously control this aspect, how does the brain figure it out?</p>

CC BY-SA 4.0
2021-09-18T04:44:21.930Z
Welcome to Psychology.SE. We work differently to many SE sites, where we have a strict policy that all questions should [show evidence of prior research](https://psychology.meta.stackexchange.com/q/993). Please help us to help you and [edit] your question to provide more information on what you have read on this subject, what made you ask this question, and any problems you are having understanding your research. If you found nothing, what did you Google? This helps to provide an answer which will be more helpful. If you still have trouble with this, please visit the [ask] page or [meta].
Chris Rogers
CC BY-SA 4.0
2021-09-18T05:55:54.843Z
It's because you have [2 eyes](https://en.wikipedia.org/wiki/Stereopsis); same principle that makes 3d movies work even though objects are projected on to a screen the same distance from you, they appear to be different distances.
Arnon Weinberg
CC BY-SA 4.0
2021-09-18T06:26:30.803Z
@ArnonWeinberg but wouldn't that only work if there is movement ?
WDUK
CC BY-SA 4.0
2021-09-18T06:48:03.473Z
Does not require movement, no.  You are thinking of parallax, different thing, doesn't require 2 eyes.
Arnon Weinberg
CC BY-SA 4.0
2021-09-18T06:58:24.000Z
Hmm i see, i was trying to find optical illusions based on shadows to trick the eyes on what was 3D or 2D which led me to wonder then if we could trick the brain on how far something was with optical illusions and see how the eyes would respond.
WDUK
CC BY-SA 4.0
2021-09-18T14:37:09.283Z
The brain can definitely be tricked, which is how optical illusions work. Depth perception, parallax, shadows, prior knowledge/expectations and focus are all thing which lead things to be perceived one way or another.
Steven Jeuris
<vision>
How does the brain know the difference between large distant objects and small nearby objects?
WDUK
# How does the brain know the difference between large distant objects and small nearby objects?

(Asked by: username_0 on 2021-09-18)

If you had two objects with words on them, one very large font and one very small font.

The large font object is further away from you than the small font object, but you could see the detail on them equally the same as they appear identical in size to you due to the scale of the objects.

How then does the brain know the difference? How do the eyes know a difference?

They say to look at distant objects to rest your eyes from the computer, but couldn't you just look at smaller font and trick the brain into thinking its looking at a large object far away?

Since we don't consciously control this aspect, how does the brain figure it out?

**Tags:** vision

> **Comments:**
> **username_1**: Welcome to Psychology.SE. We work differently to many SE sites, where we have a strict policy that all questions should [show evidence of prior research](https://psychology.meta.stackexchange.com/q/993). Please help us to help you and [edit] your question to provide more information on what you have read on this subject, what made you ask this question, and any problems you are having understanding your research. If you found nothing, what did you Google? This helps to provide an answer which will be more helpful. If you still have trouble with this, please visit the [ask] page or [meta].  
> **username_2**: It's because you have [2 eyes](https://en.wikipedia.org/wiki/Stereopsis); same principle that makes 3d movies work even though objects are projected on to a screen the same distance from you, they appear to be different distances.  
> **username_0**: @ArnonWeinberg but wouldn't that only work if there is movement ?  
> **username_2**: Does not require movement, no.  You are thinking of parallax, different thing, doesn't require 2 eyes.  
> **username_0**: Hmm i see, i was trying to find optical illusions based on shadows to trick the eyes on what was 3D or 2D which led me to wonder then if we could trick the brain on how far something was with optical illusions and see how the eyes would respond.  
> **username_3**: The brain can definitely be tricked, which is how optical illusions work. Depth perception, parallax, shadows, prior knowledge/expectations and focus are all thing which lead things to be perceived one way or another.  

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