Grouping by Contrast


Yesterday we talked about 7th annual Best Illusion of The Year contest. We covered the winner and one of the finalists, and I think it wouldn’t be fair if we moved on without mentioning one particular interactive animation. More specifically – the illusion that won the second prize.

Created by Erica Dixon, Arthur Shapiro and Kai Hamburger “Grouping by Contrast” presents luminance levels of four disks modulating in time. The top two disks become white when the bottom two disks become black (and viceversa), but when they are placed against a split background, the disks group together along the diagonals giving the illusion their modulation is out of sync. This grouping pattern follows the contrasts of the disks relative to their backgrounds. You are welcome to test this theory by playing with the interactive button below.

© 2011 Erica Dixon, Arthur Shapiro & Kai Hamburger
  • Wow. Impressive.

  • roarshack

    i didn’t get it until i saw the remove background button :O

    and awesome last name, Kai Hamburger ;)

  • Care Bear

    Cute, if you’re into dots.

  • Rahowa

    I like this . If you wouldn’t have had the remove background button , I wouldn’t have believed it . BTW ; Thanks for the page . I hope it’s making you some good money . It’s fun

  • Yannick Anckaer

    nice one, trippy duuude

  • crosstime_saloon

    Hippy Trippy – Like it!

  • Padma

    that is sooo cool! hahaha it is a cool lastname!

  • tom

    I love this one because usually you can see the trick and force your eyes to not see it but here there’s no way to see the two side-by-side disk change color simultaneously

    Great one!

  • Devam Doshi


  • t


  • DAN

    Is there a way to find an illusion from a particular date? For example, how can I get to yesterday’s illusion.

  • ZL123

    Ooohhh. But no, they look fine to me. After I took it out a couple of times, I put it back a couple of times, I could see it moving the same colour! Because left is dark and right is bright.

  • I am very surprised in Grouping by Contrast! If possible I will use it in our presentations (with the name of the makers). In that case, how can I do that?

  • Anonymous

    I didn’t get it at first. by what it said, but I pressed the button and was like, whoa!

  • WOW

    it is flashing look at the top one its not doing that so….. ya its flashing on and off

  • kira

    if u actually cover all but one of the dot, and switch the backgroud off, the sync is off. the dot has a faster flash rate with no background as compared to with

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