# A remarkably persistent optical illusion **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [August 20, 2009, 5:35am UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041 "2009-08-20T05:35:53Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [August 21, 2009, 11:06am UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/21 "2009-08-21T11:06:42Z")
> [@Eyebrows\_0f\_Doom](#): > > :eek: :eek: > > I HAD to cut & paste that one into Photoshop to make sure. I could not believe the blue & yellow were the same color. Just noticed my link didn’t work as intended, but you found it anyway. From the page my link goes to, click “Colour perception”. Illusions 1 and 2 are especially odd. ---
**Author:** ![Shot\_From\_Guns](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@Shot\_From\_Guns](https://boards.straightdope.com/u/Shot_From_Guns)\ **Post date:** [August 21, 2009, 3:02pm UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/22 "2009-08-21T15:02:39Z")
> [@Colophon](#): > > My point is that this one is “cheating” somewhat by using colour mixing. It’s like presenting a yellow field with red dots (which looks orange from a distance) and a yellow field with blue dots (which looks green from a distance), and then saying “Ha! They’re both yellow!”. No, that isn’t what it’s doing at all, as far as I can tell. It’s presenting the colors in contrast to other ones, which shifts our brain’s perception. In this case, it has nothing to do with mixing. In fact, it seems to be demonstrating exactly the same principle as the link you provided. ---
**Author:** ![Delayed\_Reflex](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/delayed_reflex/32/3172_2.png) [@Delayed\_Reflex](https://boards.straightdope.com/u/Delayed_Reflex)\ **Post date:** [August 21, 2009, 4:46pm UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/23 "2009-08-21T16:46:56Z")
> [@Colophon](#): > > My point is that this one is “cheating” somewhat by using colour mixing. It’s like presenting a yellow field with red dots (which looks orange from a distance) and a yellow field with blue dots (which looks green from a distance), and then saying “Ha! They’re both yellow!”. > > If you want a _properly_ amazing colour perception illusion, check these out: > > [eChalk: Colour perception](http://www.echalk.co.uk/amusements/OpticalIllusions/colourPerception/colourPerception.html) > > especially number 2. I don’t know think it’s colour mixing, as the green sections are distinct and distinguishable from the orange/magenta stripes, so it is not quite the same as the colour mixing with pixels, etc. Even with the zoomed in picture (where the stripes are wide enough you would be hard-pressed to call colour mixing) I still see the effect. It really is more analogous to the illusions in your link - your perception of the colour is biased based on its surroundings. ETA: doh, exactly what **Shot from Guns** said :smack: ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [August 21, 2009, 5:33pm UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/24 "2009-08-21T17:33:00Z")
The OP’s link was a good one but poking around on Wiki brought me to [this](http://en.wikipedia.org/wiki/Fraser_spiral_illusion), which transcends the merely implausible to the unbelievable. ---
**Author:** ![Shot\_From\_Guns](https://avatars.discourse-cdn.com/v4/letter/s/ccd318/32.png) [@Shot\_From\_Guns](https://boards.straightdope.com/u/Shot_From_Guns)\ **Post date:** [August 21, 2009, 8:51pm UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/25 "2009-08-21T20:51:39Z")
> [@Delayed\_Reflex](#): > > ETA: doh, exactly what **Shot from Guns** said :smack: You win the username/post combo award of the day. 😃 ---
**Author:** ![DarrenS](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DarrenS](https://boards.straightdope.com/u/DarrenS)\ **Post date:** [August 22, 2009, 7:17am UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/26 "2009-08-22T07:17:39Z")
Can’t believe no one’s posted [this one](http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html) yet! ---
**Author:** ![Malleus\_Incus\_Stapes](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/malleus_incus_stapes/32/3293_2.png) [@Malleus\_Incus\_Stapes](https://boards.straightdope.com/u/Malleus_Incus_Stapes)\ **Post date:** [August 23, 2009, 2:26am UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/27 "2009-08-23T02:26:09Z")
Someone posted it in the last optical illusion thread. ---
**Author:** ![OpalCat](https://avatars.discourse-cdn.com/v4/letter/o/8edcca/32.png) [@OpalCat](https://boards.straightdope.com/u/OpalCat)\ **Post date:** [August 23, 2009, 3:03am UTC](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041/28 "2009-08-23T03:03:55Z")
I dunno, this one is my personal favorite: > **[Puzzles](https://www.thesprucecrafts.com/puzzles-4162953)** > > From Sudoku and crosswords to word searches and online jigsaw puzzles, check out our curated list of puzzles and riddles for every skill set. [Previous page](https://boards.straightdope.com/t/a-remarkably-persistent-optical-illusion/507041.md?page=1)