# Color optical illusions. My perception of the world is shaken. **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [July 31, 2005, 1:30am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954 "2005-07-31T01:30:41Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![bitwise](https://avatars.discourse-cdn.com/v4/letter/b/ea5d25/32.png) [@bitwise](https://boards.straightdope.com/u/bitwise)\ **Post date:** [July 31, 2005, 8:41am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/21 "2005-07-31T08:41:14Z")
> [@ivylass](#): > > [Can my eyes be fooled that easily?](http://www.echalk.co.uk/amusements/OpticalIllusions/colourPerception/colourPerception.html) I’ve seen optical illusions before, but not color optical illusions. > > I’m a bit unnerved, I must admit. How do I know that the red I’m seeing is really red? Saying that an object is red is not meaningful in the same way as saying that an object is 100kg. The redness of the object depends as much on you as on the object. (I don’t really want to turn this into a philosophical discussion about qualia.) For all you know, another species might see a different color when looking at the object, perhaps a color that you can’t see at all. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [July 31, 2005, 8:53am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/22 "2005-07-31T08:53:27Z")
> [@nivlac](#): > > The first two I get, but the last one is not that remarkable as some people have indicated. I see two gray cross pieces although the one on the left is a darker gray than the one on the right. Where’s this yellow cross people are seeing? Is it supposed to be the one on the right or left? Maybe I’ve just discovered some color vision difficiency on my part, or maybe my brain just refuses to be confused. Apparently you’re immune. I don’t imagine that would be defect though. Might I ask how old you are? ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [July 31, 2005, 8:56am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/23 "2005-07-31T08:56:38Z")
> [@jrfranchi](#): > > Damn, I thought illusion 3 was a hoax. > I just took a picture of it with my Digital camera. > I copied it to my desktop, opened it in Paint. > I cropped the center pieces and brought to upper left corner and delete all else. > Cut out center of each center piece and dragged them to a white area. They do match. > Under 8x zoom they are grayish with some yellow gray and some blue gray but generally the same mix. > > I couldn’t believe it. They really are basically the same color :smack: You should be able to hit the “Print Screen” button on your keyboard, then when you open Paint under File or Edit there will be a “Create new from clipboard”, “Paste as new”, or something so you don’t have to use your camera. ---
**Author:** ![Hung\_Mung](https://avatars.discourse-cdn.com/v4/letter/h/a88e4f/32.png) [@Hung\_Mung](https://boards.straightdope.com/u/Hung_Mung)\ **Post date:** [July 31, 2005, 8:59am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/24 "2005-07-31T08:59:18Z")
I keep looking at it…but the last one just doesn’t compute. I see two different things and the yellow and blue covers seem obvious. I don’t know. Those two just are NOT the same at all. ---
**Author:** ![davmilasav](https://avatars.discourse-cdn.com/v4/letter/d/e9bcb4/32.png) [@davmilasav](https://boards.straightdope.com/u/davmilasav)\ **Post date:** [July 31, 2005, 10:11am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/25 "2005-07-31T10:11:08Z")
> [@Sage Rat](#): > > Apparently you’re immune. I don’t imagine that would be defect though. > > Might I ask how old you are? I see the same thing nivlac does. Both centers are grey but the one on the right is lighter grey, not yellow. :dubious: I’m a 36 year old woman with no known history of color-blindness. ---
**Author:** ![KGS](https://avatars.discourse-cdn.com/v4/letter/k/90ced4/32.png) [@KGS](https://boards.straightdope.com/u/KGS)\ **Post date:** [July 31, 2005, 10:28am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/26 "2005-07-31T10:28:17Z")
#3 is quite bizarre. I definitely see the yellow tint in the right-hand image. Then I pull the mask over the image and see both centerpieces are identical colors. When I pull the mask away slowly, however, I see the right-hand centerpiece as light grey, with no yellow at all. And after staring at it for several seconds, I see the yellow tint gradually fade back into view. :eek: There’s another neat color trick I first saw in a college textbook (the test is probably on the Net somewhere, but I have no clue how to google for it.) What you do is stare at a color wheel for about a minute, then focus on the plain image beside it. You can clearly see the “afterimage” of the colors on the plain grey page – a photo-negative of the colors, actually. First time I tried that test, it triggered a genuine acid flashback. 🆒 ---
**Author:** ![ivylass](https://avatars.discourse-cdn.com/v4/letter/i/9de053/32.png) [@ivylass](https://boards.straightdope.com/u/ivylass)\ **Post date:** [July 31, 2005, 11:20am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/27 "2005-07-31T11:20:56Z")
> [@KGS](#): > > There’s another neat color trick I first saw in a college textbook (the test is probably on the Net somewhere, but I have no clue how to google for it.) What you do is stare at a color wheel for about a minute, then focus on the plain image beside it. You can clearly see the “afterimage” of the colors on the plain grey page – a photo-negative of the colors, actually. First time I tried that test, it triggered a genuine acid flashback. 🆒 I’ve heard of that. I think it’s some sort of eye fatigue. > [@Hung Mung](#): > > I keep looking at it…but the last one just doesn’t compute. I see two different things and the yellow and blue covers seem obvious. I don’t know. Those two just are NOT the same at all. That’s just it. The center crosspieces of the two images _are the same color_. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [July 31, 2005, 11:27am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/28 "2005-07-31T11:27:02Z")
> [@davmilasav](#): > > I see the same thing nivlac does. Both centers are grey but the one on the right is lighter grey, not yellow. :dubious: > > I’m a 36 year old woman with no known history of color-blindness. Ah well, was wondering if maybe it was a “no computers until I was 50 years old” type thing–eyes less gullible to something on a CRT monitor or such. But the crossbars should look blue and yellow. They are blue and yellow, just it requires your eyes to remove the color added by the overlying colored squares. ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [July 31, 2005, 1:02pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/29 "2005-07-31T13:02:23Z")
> [@Sage Rat](#): > > You should be able to hit the “Print Screen” button on your keyboard, then when you open Paint under File or Edit there will be a “Create new from clipboard”, “Paste as new”, or something so you don’t have to use your camera. I was eliminating any chance of tricks via Java Script. Possible to intecept the Print screen button. I decided Camera was proof vs tampering. (I watch too much MythBusters?) ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [July 31, 2005, 5:09pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/30 "2005-07-31T17:09:28Z")
> [@KGS](#): > > #3 is quite bizarre. I definitely see the yellow tint in the right-hand image. Then I pull the mask over the image and see both centerpieces are identical colors. When I pull the mask away slowly, however, I see the right-hand centerpiece as light grey, with no yellow at all. And after staring at it for several seconds, I see the yellow tint gradually fade back into view. :eek: > > There’s another neat color trick I first saw in a college textbook (the test is probably on the Net somewhere, but I have no clue how to google for it.) What you do is stare at a color wheel for about a minute, then focus on the plain image beside it. You can clearly see the “afterimage” of the colors on the plain grey page – a photo-negative of the colors, actually. First time I tried that test, it triggered a genuine acid flashback. 🆒 Haven’t seen that, but it sounds like the same effect as this: [![](http://pearl.homestead.com/files/optical_illusion_flag.gif) ](http://pearl.homestead.com/files/optical_illusion_flag.gif) Stare at it for 30 seconds or so, without shifting your eyes at all, then look at a blank white wall or paper. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [July 31, 2005, 5:38pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/31 "2005-07-31T17:38:23Z")
Not only do I see the last one as yellow and grey, but even when I use that piece to cover up the center, I still see the one on the right as very yellow, not just a differeny shade of grey. ---
**Author:** ![A.I.Wintermute](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@A.I.Wintermute](https://boards.straightdope.com/u/A.I.Wintermute)\ **Post date:** [July 31, 2005, 6:04pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/32 "2005-07-31T18:04:10Z")
I’ve seen (and have saved) a higher resolution version of #1 before, and it’s one of my favorite illusions. #3 is new to me and is pretty spectacular. It doesn’t quite edge out my favorite, though, which is [The McCulloch Effect](http://research.lumeta.com/ches/me/). ---
**Author:** ![nivlac](https://avatars.discourse-cdn.com/v4/letter/n/3bc359/32.png) [@nivlac](https://boards.straightdope.com/u/nivlac)\ **Post date:** [July 31, 2005, 10:07pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/33 "2005-07-31T22:07:38Z")
> [@davmilasav](#): > > I see the same thing **nivlac** does. Both centers are grey but the one on the right is lighter grey, not yellow. > I’m a 36 year old woman with no known history of color-blindness. > [@Sage Rat](#): > > Ah well, was wondering if maybe it was a “no computers until I was 50 years old” type thing–eyes less gullible to something on a CRT monitor or such. > But the crossbars should look blue and yellow. They are blue and yellow, just it requires your eyes to remove the color added by the overlying colored squares. Nope, I’ve been using computers for over 20 years and staring at monitors (even monochrome ones) for just as long. I’m more interested in why some people see the illusion in all its glory and others do not. That’s the intriguing thing to me. Could be just the way our brains are conditioned or wired. ---
**Author:** ![bitwise](https://avatars.discourse-cdn.com/v4/letter/b/ea5d25/32.png) [@bitwise](https://boards.straightdope.com/u/bitwise)\ **Post date:** [July 31, 2005, 10:22pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/34 "2005-07-31T22:22:22Z")
> [@nivlac](#): > > Nope, I’ve been using computers for over 20 years and staring at monitors (even monochrome ones) for just as long. I’m more interested in why some people see the illusion in all its glory and others do not. That’s the intriguing thing to me. Could be just the way our brains are conditioned or wired. I’m able to see it both ways. If I concentrate, I can see plainly that both are gray. Then, I won’t be able to see them as anything but gray for several minutes. Then, I let my mind be fooled by the illusion, and one becomes blue and the other yellow. ---
**Author:** ![dwyr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwyr/32/363_2.png) [@dwyr](https://boards.straightdope.com/u/dwyr)\ **Post date:** [July 31, 2005, 10:36pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/35 "2005-07-31T22:36:46Z")
> [@davmilasav](#): > > I see the same thing nivlac does. Both centers are grey but the one on the right is lighter grey, not yellow. :dubious: > > I’m a 36 year old woman with no known history of color-blindness. I see it the same way as you do, no yellow at all. I’ve been tested for color blindness and I don’t have any. Weird. ---
**Author:** ![Ooner](https://avatars.discourse-cdn.com/v4/letter/o/c67d28/32.png) [@Ooner](https://boards.straightdope.com/u/Ooner)\ **Post date:** [July 31, 2005, 11:33pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/36 "2005-07-31T23:33:22Z")
One of the coolest optical illusions I’ve seen, dealing with color is this: [http://www.michaelbach.de/ot/col\_rapidAfterimage/](http://www.michaelbach.de/ot/col_rapidAfterimage/) There is a ring of magenta spots on a gray background. They disappear for a moment each in succession, around in a circle. You look at the center and it appears that instead of disappearing, they are each flashing green, around in a circle. Keep staring and the dots go away completely, and it just appears that there is a rotating green dot on the background, nothing else. Blew me away the first time I saw it. ---
**Author:** ![Nic2004](https://avatars.discourse-cdn.com/v4/letter/n/4491bb/32.png) [@Nic2004](https://boards.straightdope.com/u/Nic2004)\ **Post date:** [July 31, 2005, 11:53pm UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/37 "2005-07-31T23:53:42Z")
> [@nivlac](#): > > The first two I get, but the last one is not that remarkable as some people have indicated. I see two gray cross pieces although the one on the left is a darker gray than the one on the right. Where’s this yellow cross people are seeing? Is it supposed to be the one on the right or left? Maybe I’ve just discovered some color vision difficiency on my part, or maybe my brain just refuses to be confused. I am with those who do not see differing colors in the crosses of #3. I am aware that I am classified as “Color-deficient” but I asked Ms.Nic and she said the same thing. #1 was difficult to see the B square without toggleing and #2 I saw all disks as the same. Oh well. ---
**Author:** ![Larry\_Mudd](https://avatars.discourse-cdn.com/v4/letter/l/f14d63/32.png) [@Larry\_Mudd](https://boards.straightdope.com/u/Larry_Mudd)\ **Post date:** [August 5, 2005, 7:06am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/38 "2005-08-05T07:06:03Z")
I was thinking about #3 today and decided to take [a stab at reproducing the effect](http://www.larrymudd.com/images/sdillusion.jpg). (The “yellow” lettering on the right is the actually the same grey as the “blue” background on the left.) I can see these together as quite obviously grey, but when I focus on one or the other, the colours “fade in.” Weird. The “blue” seems to stay grey longer, too. How (if at all) does this work for y’all? ---
**Author:** ![Ranchoth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranchoth/32/1066_2.png) [@Ranchoth](https://boards.straightdope.com/u/Ranchoth)\ **Post date:** [August 5, 2005, 7:57am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/39 "2005-08-05T07:57:14Z")
> [@Ooner](#): > > One of the coolest optical illusions I’ve seen, dealing with color is this: > > [redirection](http://www.michaelbach.de/ot/col_rapidAfterimage/) Freak-_y._ Well, that’s what I get for using a brain made out of monkey meat. 😃 ---
**Author:** ![sturmhauke](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@sturmhauke](https://boards.straightdope.com/u/sturmhauke)\ **Post date:** [August 5, 2005, 8:08am UTC](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954/40 "2005-08-05T08:08:37Z")
> [@Larry Mudd](#): > > How (if at all) does this work for y’all? To me it just looks like the left banner is overall brighter than the right one. With the OP’s illusion #3, the left crosspiece looks like a dark bluish gray, while the right looks like a muted yellow. When I put the mask on they both look medium gray. One of my favorite illusions is called [Benham’s Top](http://www.tsi.enst.fr/~brettel/Benham.html). It works better as a physical spinning disk or top, as opposed to an animated computer image, but you can get the idea. Basically a spinning black and white disk appears to have several different colors on it. [Here’s](http://www.michaelbach.de/ot/col_benham/) another site about it. [Previous page](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954.md?page=1) [Next page](https://boards.straightdope.com/t/color-optical-illusions-my-perception-of-the-world-is-shaken/314954.md?page=3)