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Illusion of the Week: The Coffer Illusion

The views expressed are those of the author and are not necessarily those of Scientific American.

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The Coffer Illusion, by vision scientist Anthony Norcia of  the Smith-Kettlewell Eye Research Institute, was a Top 10 finalist in the 2006 edition of the Best Illusion of the Year Contest.

The pattern contains 16 circles, but if you’re like most first-time viewers, you’re thinking, Circles? What on earth  are you talking about? I can only see a bunch of rectangles!

Okay, just trust us on this one. Look again, and 16 beautifully round circles, lodged in between the “door panels”, will pop into view in no time.

How long did it take for you to see the circles? Let us know in the Comments!


Susana Martinez-Conde About the Author: Susana Martinez-Conde and Stephen L. Macknik are laboratory directors at SUNY Downstate Medical Center. Follow on Twitter @illusionchasers.

The views expressed are those of the author and are not necessarily those of Scientific American.

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Comments 22 Comments

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  1. 1. jasongoldman 8:24 pm 03/27/2013

    About 20 seconds. Scrolling the page – adding vertical motion – was what triggered it.

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  2. 2. N a g n o s t i c 3:15 am 03/28/2013

    I saw the circles immediately.

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  3. 3. willjim95 11:26 am 03/28/2013

    Saw them midway into scanning the top first row, left to right.

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  4. 4. Hind.AQ 12:59 pm 03/28/2013

    3 seconds

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  5. 5. ringo43 2:29 pm 03/28/2013

    I saw one immediately. I had to search for three the others were quickly evident.

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  6. 6. gfletcher39 2:30 pm 03/28/2013

    Saw the 4 on the right immediately, then it took about a minute before I could see the others.

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  7. 7. klondikejack 3:40 pm 03/28/2013

    I also saw the circles immediately…

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  8. 8. MikeB 4:15 pm 03/28/2013

    Thanks to the scrolling tip I saw them after about 5 seconds. Oddly, though, continued viewing makes them disappear and then reappear repeatedly.

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  9. 9. AntiMufa 1:09 pm 03/29/2013

    Primero mire la imagen, sin leer la consigna y vi cuadros.
    Leí la consigna “ver 16 círculos” y no vi nada.
    Cuando leí dónde estaban los vi.

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  10. 10. HalehAzadeh 2:52 pm 03/29/2013

    maybe 30 or 40 second and i found all 16

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  11. 11. babe471119 5:57 am 03/30/2013

    I’ve been at it for a while and I can’t see a thing….

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  12. 12. hpvpp 8:01 pm 04/3/2013

    If we allow the mind to fill in some detail we can see another circle around the cross in the middle and likewise in corresponding places though I suspect those are not the ones intended.

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  13. 13. AbbieNormal 1:43 am 04/4/2013

    Took 15 to 30 seconds for them to appear for me. I see “circles” best on top or bottom to left or right of my center of vision. Circles are vague in my center of vision but appear clearer off center focus of vision.
    Nice illusion.

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  14. 14. JAMichon 3:26 am 04/4/2013

    This is a neat illusion, ranking with other “mind set” illusions, of which the wellknown Dalmation Dog is the prime example: once you have found the circles, next time they will appear faster, or even be there already if you start looking at the display.
    Answering the author’s question: first time it took me may be 8 to 10 seconds, before I saw the circles “light up” in the righthand column. Then moving my eyes over the display the others appeared (in rows). The fixation cross in the center does not really help, perhaps moving one’s eyes (or the display) triggers effect more quickly (cf. comments 1, 3, 8, and it might help commentators 11 and 12).

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  15. 15. JAMichon 3:45 am 04/4/2013

    Further to my earlier comment (# 13), the fixation cross in the center is about the worst place for the effect to manifest itself. Similarly, looking at the center of any one of the 6 rectangles “surrounding” the cross, hinder the appearance of the circles. Looking at a spot in between two vertically arranged rectangles has immediate beneficial consequences: circles all over the display!

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  16. 16. Ian St. John 1:18 pm 04/4/2013

    It took me about five seconds after reading the claim that they were there ‘between the panels’. However, I can only see four to 12 at a time. I cannot seem to see all 16 at the same time.

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  17. 17. daimiles 8:38 pm 04/5/2013

    Saw the right hand set as soon as I scrolled down, then the others as I scrolled back up.
    Then I read these comments.

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  18. 18. jonmeads 8:46 pm 04/6/2013

    It took a while to find all 16. The eight on the far right and far left appeared within a few seconds but I really had to work to see the circles in the inner columns.

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  19. 19. soshiny 3:21 am 04/22/2013

    It took me about 5 seconds to see the first four on the R hand side, then another search revealed the others. A total of about 15secs.

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  20. 20. Knowledge1 2:24 pm 05/20/2014

    It took me about 15 seconds.

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  21. 21. Frank781227 1:18 pm 08/15/2014

    It took me about 1 or 2 seconds to see the circles.

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  22. 22. Terijo 1:30 am 08/30/2014

    I didn’t time this. But the first time I looked, I did not see circles. The second time I looked, I could see them on the far right and far left columns.

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