Counter Intuitive Ghostly Square

This one today was one of the 2010 Optical Illusion Contest finalists. The only reason it didn’t win, was because of spectacular Magnet-Like Slopes that competed at the same time. Anyway, despite its relatively simple nature, the effect it holds is more than entertaining. Here’s what you have to do to understand the illusion: observe the 4 little moving dots. As they move further away one from another (expand – if you wish), and when their path crosses bigger circle’s surface – the ghostly contours appear. It seems as if the smaller dots represented a corners of an expanding and shrinking square. In reality, there are no contours present, and they were only placed here by our brain who struggles to interpret the animation. It is well known that the visual system will often generate illusory contours and surfaces in order to fill-in this missing information. It is widely believed that the visual system does this in order to provide the best overall explanation of the images that form in our eyes.

optical_illusions_illusory_contours

66 Replies to “Counter Intuitive Ghostly Square”

  1. That’s Cool
    All this stuff about ‘our brain not comprehending such and such’ makes me feel primitive

  2. At first I didn’t see anything, until I opened the animation in a new screen by clicking on it. Than it run smoothly and undistorted….

    When the big grey circles are moving inward, you can see the square through it (in you brains appently).

  3. Nice illusion. It works because of the big grey circles who go over the white square. The ‘ghost contours’ are there where de grey overlaps the white.

    Very nice indeed!

    I am wondering, is it possible to see the ghost square without the white dots?

  4. Awesome Anonymous, you should feel the opposite. When we have conflicting information, our brains rival the speed of a computer, determining what should be there. It calculates many outcomes of possibilities, and then decides which one is the most accurate.

    Even though in this case, our brains got the wrong answer, there’s no way you should feel even remotely primitive =D

  5. This is very good, but the animation on this page is lousy. There is too much lag, and then there are graphic artefacts to deal with as well. I had to open the gif file by itself to see the illusion.

  6. I don’t get it!!! I didn’t see anything out of the ordinary… Only 4 little moving dots and the lines showing they moved and the 4 bigger moving dots and their lines… Nothing else……… hmmmm

  7. My brain isnt providing an explanation for me. I dont see the contours at all. Wonder what that means??

  8. i find it easier to see if you make an imaginary square with the 4 small circles as the corners

  9. if you concerntrate on the straight lines you get a square but if you think more about the circle the illusion lines end up more rounded and even make a circle ;)

  10. This is very cool, but I found more to it. Because of a scaling issue, the central square has the right edge missing when the image is displayed in the google widget. The surprising (to me) result is that if the right edge is not there, you can’t see the right half of the ghost square! :)

  11. To me the sides of the phantom square seem slightly curved (convex). Has anyone else noticed this?

  12. Maybe this is the artifact that earthling was talking about, but if you take a screenshot, you can actually see that there are “contours” where it appears that the white lines are bending towards the big circles. There are a few pixels that actually are out of alignment with the rest of the line. If that is all that there is to this illusion, then it isn’t an illusion at all – it is actually doing what is claimed to be only in our minds.

  13. It took me a LONG time, but I eventually saw it. I see a nonexistant square, where the 4 white dots are the corners of it. It is at 45 degrees to the white outlined square

  14. Lacy, I needed to open it up in another window and then the lines disappear and you see the illusion, fantastic

  15. AMAZING… the white dots appear to have “bow-waves” when they pass through the grey circles. However I’m not sure they are “square”. In other words, the white dots seem to represent the corners of a more rounded square to me.

  16. I first didn’t see it. Read the comments opened up gif in new tab and then saw it.

    What you see is a diamond shape following the dots moving outwards.

  17. I watched the dots at first, didn’t really get what I was supposed to be looking at – then noticed the dots I weren’t looking had something different going on.

    Look directly in the middle of the square and don’t move your eyes, as the large dots cross the boundary you will see the other box appear in negative.

    Very clever!

  18. Oh… this is strange. First look, nothing. I then read the comments.
    It works better if you open it without text as a distraction. I looked at it and the box “came up” when the grey circles were overlapping it.
    Weird thing is, it only worked the first time. Afterwards, I try too hard to see it, and it doesnt happen again! Obviously my brain won’t be fooled by the same thing more than once…

  19. It took me quite a while to see this.
    First of all you HAVE to click on the animation to get it in a window of its own, somehow the animation on this page is flawed.

    Second of all try not to look at the animation at all, instead focus on an imaginary spot in the center of the square, then out the corner of your eyes you should be able to see the ghostly square.

    Actually this seems to generate different ghostly images for me, sometimes I see the ghostly square where the original white square was even when it’s covered by the large gray circles. Sometimes I see a ghostly square linking the 4 white dots (I think that’s what I’m supposed to see), and sometimes I see a ghostly circle formed by the 4 white dots

  20. It took me a litte bit to see it. First you have to click on it to get a better view of it.. it’s too distorted on this page. Then, it works better if you stare at the empty space in the center. Don’t focus directly on the moving balls.

    The animating in the windows sidebar gadgets causes the CPU to go 100% on single core PC’s. 50% on dual core.. it’s killing performance. Please do like you used to and use a static image for the gadgets..

  21. It’s caused by the edges of the larger circles intersecting the lines and the positions of the smaller circles indicate to our minds the corners of the ghost square. Our minds see the lining up of the small circles with the breaks in the lines and create a ghost line.
    Best seen when you look in the center of the image.

  22. Wow, this one gives a completely different illusion if you are looking at it in the mac widget or on the site in full size.

    In the Mac widget it looked like the white box would stretch out a bit when the white dots hit the gray ones. But in the full size I can totally see the box with the white dots representing the corner bit.

    Very cool.

  23. I couldn’t see it at first because the image most was moving so jerkily and had a lot of lag to. Opened it in a new window and had the same problem. Opened it in a new BROWSER and problem solved. IE8 just wasn’t working, used Firefox.

    So now I FINALLY see the illusion and it’s actually pretty cool

  24. i can’t see the illusion very well…and the picture is lagging a lot…if theres a way make it better for ie8…thank you

  25. i wasnt getting it at first i thought the square in the middle was not ment to be there and then im thinking what the hell?. but now im looking at it as if a square is being thrown up into the air and it is quite cool.

  26. if you look closely enough the square that the small circles can be seen because the darkness of the color there are many shades of black and the programmer used a slightly different shade between the smaller moving circles as it expands that gives you the illusion

  27. Not a suprise to me that the slopes one won.. if you need to have this illusion explained (I couldn!t see it at first) then it’s an automatic fail.

  28. I don’t get the big deal. Isn’t it the simple fact that the white circles exiting the same time as the grey circle enters and that creates the square?

  29. Hey! This is an awesome illusion.
    I figured out something with this – the motion of the circles is needed to create the illusion. I grabbed this and opened it in Photoshop and flipped through the layers, and it looked totally normal at a standstill. Although I just look way to deep into thins… awesome website and illusion!

  30. This one took me a while to see. The only way I could see it was to stare at the center of the animation. Then it slowly appeared. I could see the square.

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