# How and why does this optical trick work?

**URL:** <https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493>\
**Category:** Factual Questions\
**Created:** [January 27, 2013, 12:54am UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493 "2013-01-27T00:54:01Z")\
**Posts on this page:** 7\
**Page:** 3

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**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\
**Post date:** [January 27, 2013, 10:03pm UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493/41 "2013-01-27T22:03:40Z")

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> [@njtt](#):
>
> Whatever. (Presumably you learned that from the link I posted.) My point was that the effect does not depend on the faces being distorted, or in any way weird, extreme, or unusual.

Or, you know, by looking at the original picture. Regardless, the faces _do_ change size relative to each other, with some heads being larger. That might be a significant factor.

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**Author:** ![Saint\_Cad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saint_cad/32/18907_2.png) [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)\
**Post date:** [January 27, 2013, 10:13pm UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493/42 "2013-01-27T22:13:25Z")

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I remember one researcher was studying why people recognize why charactures of famous people are more recognizable than accurate drawings. His theory was that the brain recognized faces by building a characture in the memory and then when they see a face the brain tries to match charactures. If that’s accurate then this might be a result of that effect.

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**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\
**Post date:** [January 28, 2013, 2:20am UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493/43 "2013-01-28T02:20:56Z")

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I recall seeing an earlier version of this illusion, which I believe was created for the original 2011 study. It uses photographs of average faces, where expression, orientation, scale, and lighting are all kept constant. The only thing that varies between photos is the proportions of each face.

… Here we go, the [researcher’s web page](http://mbthompson.com/research/) has the [video I recall](http://www.youtube.com/watch?v=wM6lGNhPujE).

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**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\
**Post date:** [January 28, 2013, 2:52am UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493/44 "2013-01-28T02:52:14Z")

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I have only one working eye and I see the effect quite plainly.

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**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\
**Post date:** [January 28, 2013, 2:58am UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493/45 "2013-01-28T02:58:19Z")

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Article here

> **[Flashed Face Distortion Effect Makes Ordinary Portraits Look Hideous](https://petapixel.com/2012/05/22/flashed-face-distortion-effect-makes-ordinary-portraits-look-hideous/)**
>
> If you ever create a slideshow of portraits, you might want to avoid showing them aligned side-by-side with a gap in between. The video above shows a

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**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\
**Post date:** [January 28, 2013, 5:21pm UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493/46 "2013-01-28T17:21:17Z")

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How do I keep my eyes on the cross and still see the pictures?

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**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\
**Post date:** [January 28, 2013, 6:14pm UTC](https://boards.straightdope.com/t/how-and-why-does-this-optical-trick-work/648493/47 "2013-01-28T18:14:58Z")

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> [@Jake](#):
>
> How do I keep my eyes on the cross and still see the pictures?

You’re supposed to _look_ at the cross, not actually touch it with your eye…

🙂

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