The Coffer illusion

Okay, look at the photo of the door below. Time yourself from the start to see how long it takes you to find the circles.

How many circles do you see? Do you see any?

There are sixteen circles. Do you see them? If you don’t, and for an explanation, go to the next page by clicking “read more”

Here’s a reveal: one circle. The rest should now be obvious.

This is the “Coffer Illusion, explained like this:

This fascinating image was created by Anthony Norcia of The Infant Vision Laboratory at Smith-Kettlewell. It is referred to as the Coffer Illusion due to its close resemblance to the 3-dimensional coffers usually found on wooden doors (a coffer is a decorative sunken panel). Dr. Norcia claims that the illusion works because segmentation cues are pitted against the observer’s strong conviction to interpret the image as a series of rectangular coffers with closed boundaries.

When Dr. Norcia tested this illusion on a group of 100 people, the average time taken to see the circles was 45 seconds. A few individuals were able to spot the hidden shapes after only 10-15 seconds, while other persons took much longer and/or required explicit hints to finally see the circles. How long did you take?

I didn’t time myself, but it took me a while.



  1. John
    Posted August 11, 2017 at 3:57 pm | Permalink

    A couple seconds.

  2. Craw
    Posted August 11, 2017 at 3:58 pm | Permalink

    It took only 2 or 3 seconds to see circles but only on the rightmost column. My right eye is a bit bleary, which might have contributed. Then I could see the others but it took effort. I am not convinced I can see all 16 at once!

    • Ken Phelps
      Posted August 11, 2017 at 7:12 pm | Permalink

      Ditto on the right column first.

      • Posted August 11, 2017 at 7:47 pm | Permalink

        Same here. Right one first then the left one, then the second to left (more difficult), and still very hard to see the one in the second to right column, despite knowing where to look and focus.

        • Merilee
          Posted August 11, 2017 at 7:54 pm | Permalink

          I wonder what’s different about that one column?

          • alexander
            Posted August 12, 2017 at 1:49 am | Permalink

            “I wonder what’s different about that one column?”

            The structures inside the circles or rectangles in the first and fourth columns are symmetrical, while those in the structures in the second and third column are not. We spot this symmetry first, which leads us to look for further symmetries (unconsciously). The prediction of things by our brain is one of the fundamental mechanisms in perception, we see first what we expect to see (and this is why it is difficult to spot the hidden lizard or snake in “spot the lizard” images because we look for obvious details, like ears or tails, which then are hidden). We enjoy classical music because we hear what we expect and know, and this is the reason that you have to listen to a classical piece a few times before to enjoy it fully).

  3. eliz20108
    Posted August 11, 2017 at 4:05 pm | Permalink

    I could not see them at all until I read the explanation.

  4. Posted August 11, 2017 at 4:05 pm | Permalink

    Maybe 6 or 7 sec

  5. Posted August 11, 2017 at 4:06 pm | Permalink

    Same with me, just two seconds or less to see the rightmost ones, but could not see the leftmost ones. But if you scroll the image while looking, all are obvious.

    • Craw
      Posted August 11, 2017 at 6:44 pm | Permalink

      Indeed. Scroll and defocus, and suddenly I can see all 16 at once.

  6. Mike Hagan
    Posted August 11, 2017 at 4:09 pm | Permalink

    Took me about 8 seconds

  7. Posted August 11, 2017 at 4:11 pm | Permalink

    Weird. I saw the lower right circle in about one or two seconds, and after that the rest just stood out automatically.

    • Lee
      Posted August 11, 2017 at 6:36 pm | Permalink

      Same here. Once I saw one example, all the rest jumped out. It seemed too easy. I was expecting something like “32 circles”, and that I would need to go hunting. I’m usually slow at things like this.

  8. Merilee
    Posted August 11, 2017 at 4:38 pm | Permalink

    Pretty quick to see 4, then 7, then 10, then 14 of them, but never could see the middle 2 in the 2nd column from the right.

    • Merilee
      Posted August 11, 2017 at 4:52 pm | Permalink

      Finally saw the last two.

  9. Posted August 11, 2017 at 4:42 pm | Permalink

    I needed the cue.

    • rickflick
      Posted August 11, 2017 at 5:05 pm | Permalink

      Me too. I waited 5 seconds before looking for a clue. Is that cheating?

  10. moleatthecounter
    Posted August 11, 2017 at 4:49 pm | Permalink

    16 – first in about 2-3 seconds, then the rest within 2 more seconds. No cue.

    Fabulous illusion!

    • Torbjörn Larsson
      Posted August 11, 2017 at 4:52 pm | Permalink

      Same here. They filled in gradually from the first circle seen.

  11. Steven Pounders
    Posted August 11, 2017 at 5:04 pm | Permalink

    About 30 seconds. But once I saw them, I was most surprised that it had taken me any time at all.

  12. Terry Sheldon
    Posted August 11, 2017 at 5:16 pm | Permalink

    I could see the rightmost four immediately, the rest a few seconds later.

  13. Zwirko
    Posted August 11, 2017 at 5:21 pm | Permalink

    The only circle I see is the red one.
    Should I be worried?

    • rickflick
      Posted August 11, 2017 at 7:11 pm | Permalink

      No. The Senate’s Subcommittee on Investigations has been adjourned.

      • rickflick
        Posted August 11, 2017 at 7:13 pm | Permalink

        The Army–McCarthy hearings, I mean. 😎

  14. bbenzon
    Posted August 11, 2017 at 5:37 pm | Permalink

    I looked at the image before I read the prose for a few seconds. Didn’t see any circles. Then I read the prose and looked at the image again. I saw the circles within seconds.

  15. Posted August 11, 2017 at 5:55 pm | Permalink

    A few days ago, when I first saw this illusion, I didn’t see the circles and quickly gave up. This time, I saw the circles from right to left almost instantaneously. I’ve never been very quick on these kinds of puzzles, for whatever reason.

    • Diane G.
      Posted August 12, 2017 at 2:35 am | Permalink

      Same here; can’t remember where I first saw it, though, can you?

      I didn’t spend much time on it then; this time it jumped out at me before I even began to read the text.

    • gravelinspector-Aidan
      Posted August 12, 2017 at 9:03 am | Permalink

      Similarly here too. I saw it a day or two ago on Twitter – and on a different screen, which displayed it in a vertically-squeezed form. I couldn’t see the circles at all. In landscape format on the laptop – and presumably without the scaling function my phone used on Twitter, it took about 30 seconds to see the circles. As others say up-thread, the ones on the right appeared first, spreading left.

  16. Kevin
    Posted August 11, 2017 at 6:02 pm | Permalink

    Nearly as soon as I saw it.

  17. rickflick
    Posted August 11, 2017 at 7:19 pm | Permalink

    I’ve noticed that a huge(covfefe) number of commenters admit to being miraculously good at this puzzle, but few are willing to append a shameful confession of abject failure. I’m detecting a small selection bias. 😉

    • Posted August 11, 2017 at 7:51 pm | Permalink

      Ironically, to claim that you ‘detected’ selection bias, sounds like selection bias to me too: you ASSUME selection bias, because that seems to be a plausible explanation for your observation, but unless you actually test for it, you can’t state that you ‘detected’ it: it’s technically possible that everyone spoke the truth.

      • rickflick
        Posted August 11, 2017 at 7:58 pm | Permalink

        I’m sure everyone spoke the truth. After all this is WEIT. But, self selection occurs too. Those who succeed comment. Those who don’t succeed crumble in dismay and fear to admit failure. Am I alone it this shame? 😎

    • Jeff Chamberlain
      Posted August 11, 2017 at 10:07 pm | Permalink

      I admit to abject failure. I’ll pass on shameful, though. (I’m consistently awful at optical illusions.)

      • rickflick
        Posted August 12, 2017 at 7:48 am | Permalink

        Thanks for speaking up. I no longer feel so isolated. 😎

        • Merilee
          Posted August 12, 2017 at 9:50 am | Permalink

          Maybe if you took your sunglasses off you’d see better, Rick🤓😁

          • rickflick
            Posted August 12, 2017 at 5:28 pm | Permalink

            Ah! There they are. I’ve been looking for them all day. 🙄

            • Merilee
              Posted August 12, 2017 at 6:14 pm | Permalink

              He sees the light🌞

              • rickflick
                Posted August 12, 2017 at 8:51 pm | Permalink

                …through a glass darkly. 🔍

              • Merilee
                Posted August 12, 2017 at 11:06 pm | Permalink

                But is the glass half empty or half full?

              • rickflick
                Posted August 13, 2017 at 8:00 am | Permalink

                The glass is about 2/3 full. It has big, chewy, tannins, is quite dense and complex.
                One might even say bold. It’s a mild domestic burgundy without any breeding, but I’m sure you’ll be amused by it’s presumptions.

              • Merilee
                Posted August 13, 2017 at 9:25 am | Permalink


  18. J Cook
    Posted August 11, 2017 at 7:56 pm | Permalink

    The first vertical 4 on the right immediately and the rest in 10 seconds or so.

  19. Dionigi
    Posted August 11, 2017 at 8:07 pm | Permalink

    Took me ages to find the circles but the main point is why is this different for different people. Coming up with amusing optical illusions is fun but where is the science?

  20. Mary L
    Posted August 11, 2017 at 8:15 pm | Permalink

    Took about 5 minutes to see one, then I could easily see the rest.

  21. Posted August 11, 2017 at 8:19 pm | Permalink

    Maybe one second, maybe two – but interestingly (it may have only been a coincidence) it was scanning down and seeing the sentence “there are sixteen circles” that did it. I looked up and saw them immediately. I didn’t see them in the second while I wasn’t sure if they were really there.

    • Posted August 11, 2017 at 10:53 pm | Permalink

      Further experimenting (on myself) suggests it’s the act of scanning down quickly that made the circles appear, not the text I scanned down to

      • Diane G.
        Posted August 12, 2017 at 2:37 am | Permalink

        Ah, that’s it! Put the figure in motion and they jump out at you.

        • Rexsalad
          Posted August 12, 2017 at 7:10 am | Permalink

          After about 30 seconds, looking at the sixteen focussed me, too.
          Only then I saw 5×5.
          Probably because I’m still kind of drunk.

  22. Wayne Y Hoskisson
    Posted August 11, 2017 at 9:18 pm | Permalink

    I have seen this illusion before. Staring at the X in the center makes the circles pop out quickly. The circles with the most dark bars pop out easier than the others.

  23. infiniteimprobabilit
    Posted August 11, 2017 at 10:37 pm | Permalink

    I saw all sixteen straight off. That is, I recognised one (top right) straight away and instinctively deduced that all the other junctions of lines should be circles and when I looked, there they were. They seem so obvious, I can’t understand how anybody could miss them. I do agree the second-to-right column is the least obvious, due to the lower contrast between the vertical and horizontal lines.

    I *was* ‘primed’ to look for circles by having read the text of this post in my email before I called up this web page. And also I was expecting some sort of visual illusion. So maybe without that ‘priming’ it would have taken me longer to notice.


    • ratabago
      Posted August 12, 2017 at 12:33 am | Permalink

      I think priming is important here. I had noticed the right hand column of circles before I had finished reading the first sentence. Looked straight at the central x, and defocused. All 16 circles leapt into view. time spent looking directly at the image was probably less than a second. If I wasn’t primed I don’t know how long it would have taken, or if I would have noticed the circles at all.

  24. Posted August 12, 2017 at 1:50 am | Permalink

    A couple seconds. I think it’s because 1)I knew it was an optical illusion. 2) I knew to look differently at the picture that I first saw.

  25. John Crisp
    Posted August 12, 2017 at 2:10 am | Permalink

    Probably about 10-15 seconds, starting on the right column. Doubt I would have seen them if not primed and they still don’t jump out at me.

  26. Johan Richter
    Posted August 12, 2017 at 3:03 am | Permalink

    I lookly quickly at the first image, did not see the circles, and then looked at the second image with the red circle. I still did not see the circles but when I looked at the first image again more closely I saw the circles on the right side and after that I could see all of the,

  27. Steven in Tokyo
    Posted August 12, 2017 at 3:04 am | Permalink

    I saw the top left-hand circle almost immediately, and all of the others clicked into place like a reverberation wave across water. My eyes (not as good as they used to be, with quite a few ‘floaters’ now) seem to be able to turn them on and off at will. Interesting.
    (I’ve just allowed myself a written single-adjective sentence for the first time in my life; I wonder [not really!] where that comes from …)

  28. Eric Shumard
    Posted August 12, 2017 at 7:51 am | Permalink

    There are 3 additional circles within the text “How many circles do you see?”

  29. John Gibson
    Posted August 12, 2017 at 7:58 am | Permalink

    I had a look at it yesterday, but gave up when I couldn’t spot any. I came back to it today and saw the first one, in the right hand column instantly, and after a couple of seconds, saw the others. Perhaps my mind was subconsciously working on it between visits.

  30. Hempenstein
    Posted August 12, 2017 at 8:31 am | Permalink

    ~30sec. I was thrown off by the fused, vaguely circular appearance of the third column. When I decided that wasn’t it, I guess I started looking at the center of the coffers. Nada. But looking at the bars between the coffers they’re instantly visible.

  31. Mike
    Posted August 12, 2017 at 9:16 am | Permalink

    Once seen, can’t stop seeing

  32. damboni
    Posted August 12, 2017 at 9:50 am | Permalink

    10 seconds, and I, too, saw the rightmost column of circles first.

  33. Posted August 12, 2017 at 10:09 am | Permalink

    It only took a second or two to see the circles — the first time. After that, though, I couldn’t make them pop out at me. I think I was so eager to see them that my eye wouldn’t stop wandering. Finally I gave up. I looked directly at where one of the circles would be. There it was. The others appeared. As long as I’d look where they should be, they’d be there. As soon as I looked at the X again or the squares, they’d be gone.

  34. Steve Brooks
    Posted August 12, 2017 at 11:23 am | Permalink

    It took about ten seconds for me to see the four circles in the right-hand column. As for the other circles, I got glimpses of them in my peripheral vision, but when I looked directly at them, they disappeared.

  35. nicky
    Posted August 12, 2017 at 3:30 pm | Permalink

    Took me a while, a dozen seconds or so. Didn’t really time it. I wonder if I would have seen any if there had not been the question about how many circles one could see.
    For the best visual and optical illusion site go to
    . I think he works at Tubingen University

    • Sixtus
      Posted August 12, 2017 at 4:32 pm | Permalink

      Great recommendation. Thx.

  36. Posted August 12, 2017 at 4:55 pm | Permalink

    I can see another dozen or thereabouts.

    Firstly I noted the sixteen referred to all bisected horizontally by the ‘panel lines’.

    I reasoned that the same illusion might also apply around the vertical panel lines. Sure enough, with patience, they can be seen too, only slightly less defined than the obvious sixteen that are horizontally bisected.

    • nicky
      Posted August 13, 2017 at 1:26 am | Permalink

      Yes! I didn’t see that at first. But they remain somewhat ‘cut’ in the middle, and sometimes segue into a vertical sinusoid.

  37. Larry Cook
    Posted August 12, 2017 at 8:02 pm | Permalink

    I tried looking at it on my phone without seeing any circles, but when I used my laptop I saw all 16 in 45 seconds. Now I can’t not see them. My wife saw them in 5 seconds, but that’s no surprise since she does everything better than I do.

  38. The Rose
    Posted August 13, 2017 at 12:41 am | Permalink

    As a painter of —
    Architecture, I’m seeing,
    All of the circles, and then?
    Went to “looking”, and “tooking”.

  39. Posted August 13, 2017 at 3:42 am | Permalink

    I love stuff like this! Please keep the illusions coming

  40. Mary L
    Posted August 13, 2017 at 7:16 pm | Permalink

    rickflick – Is your first wife on top of a bookcase?

  41. harrync
    Posted August 13, 2017 at 11:27 pm | Permalink

    It took me a while to spot them – longer than reported by most others – especially the third column. But when I took those so-called intelligence tests, that often included spacial recognition problems, I usually did quite good – like 99+ percentile good. But it was about 50 years ago that I took those tests – maybe I have deteriorated a bit since then.

  42. Posted August 14, 2017 at 3:35 am | Permalink

    I saw them immediately, before reading the text, and I was surprised that most people have to look for them.
    I thought the illusion might refer to the nine larger circles, which I see at the intersections of groups of four circles. But the explanation makes no mention of that.
    The third column is decidedly less prominent than the other columns.

  43. Posted August 14, 2017 at 11:38 am | Permalink

    Always starts in the lower right for me, about 1 second after the image is all visible. Then they “fill in” going up and then down the columns.

  44. ethologist
    Posted August 15, 2017 at 1:21 pm | Permalink

    I saw them fairly quickly (a few seconds) but what was weird was that I saw the ones down the rightmost column more quickly, and still see them more easily. They seem to “pop out” and stay that way, while the other ones blink in and out.

    • Merilee
      Posted August 15, 2017 at 1:48 pm | Permalink

      Same for me.

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