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By on February 21, 2009, with 35 Comments

Now, I really love this one! Larry from Michigan sent me an image I couldn’t miss sharing with you. What we have here is a classic example of “Slanted Lines” illusion, just like the one we published on Monday. The usage of the effect is more advanced this time, since it additionally exploits the nature of the object presented. A seesaw (also known as a teeter-totter or teeter board) is a long, narrow board suspended in the middle. As one end goes up, the other one goes down. When we first see the example below, it looks logical that the right end went down due to heavy triangle positioned on it. The illusion shows just what you naturally expect, but the raw truth is that the seesaw is balanced perfectly horizontal, and doesn’t outweigh – nor left, nor right. You can easily prove this by squeezing your eyes, till you just see the outlines of the seesaw. Thanks for stumbling and sharing this!

Update 1 (02/22/2009): Since yesterday, I have received this enhanced animation from visitor that goes by the name Mr. Anonym. His version might help you in seeing the effect little better. You should be able to spot the moment after which the seesaw gets slanted.

Update 2 (02/22/2009): Alessandro aka SuperSandro sent another example where he modified this illusion. Now the seesaw is actually slanted, but appears perfectly balanced. Here is what Alessandro wrote – “Hi! Today I’m happy to send you this attached file. It’s the same as slanted Seesaw, but rotated for 4 degrees on the rectangle’s side. It seems to be horizontal, but of course it is not.”

  • IRainman

    and whether there is an article explaining why our brains perceive a picture like that?

  • mati


  • ojas pashankar

    This is my first ever comment!!

    Just wanted to thank you for such an Awsome collection.. keep up the Awsome work!!

    Obv, liked this illusion But I love all of them…

  • Anonymous

    WOW thats awsome!!!!

    One of the best illusions ive seen in a long time!

  • Anonymous

    Nice one, huh?
    I love it!

  • Drummermean

    Owned my brain, that’s for sure.

  • Andrew

    Yea, our brains do their best and most efficient way to perceive an image but sometimes, it’s not good enough. It’s tricky sometimes to figure out why that happened.

  • FaQ


    IRainman, here’s a website I found that tries to explain away the mystery around the basic optical illusions you might have seen on this site and elsewhere.


  • Anonymous

    wow thats cool…lol

  • nud


  • Smudge

    Great illusion!

    Our brains can be so stupid sometimes.

  • Anonymous

    its weird how our minds do that

  • OuRaNoS


  • Anonymous


    Second commenter!!!!

  • Anonymous

    whoa this is cool a great effect

  • Anonymous

    you dont need the downwards arrow on one end, but it helps.
    if you measure the distance, its perfectly flat. interesting

  • ScrOuch

    This is really cool!
    It is always fascinating, how our brain is working.

  • Optiguy

    I love this one! I usually don’t take much interest in the generic slanted line illusions, but this one is awesome!

  • Tysss

    I see the third picture not balanced.. left part is more down.

  • Felix


  • Anonymous

    A perfect example of the fact that things are not always what they seem!

  • LPizzle


    thanks to larry of michigan, mr. anonym, and alessandro for helping make it even better!

    glad to see so much participation in your illusions vurdlak!

  • Anonymous

    Sorry, but the last one doesn’t look straight to me. Good illusion though.

  • Yum nub yum

    Great illusion, but I’m sorry to say the animated one is a fake. If you hide the whole animated picture except the top right triangle, you can see it moving whereas it shouldn’t.

    • fully

      true true i agree

  • random

    also, try holding your pointer right at the line on the seesaw. You can see the line move below the mouse on the second picture

  • DaEgg


  • Alice

    actually the one on the bottom isn’t very well-made. i see it as slightly slanted the other way.

  • http://krokrow-krokers.blogspot.com krokrow

    wow.. really great illusion

  • notarealname

    woa is me or is the pictr comin closr

  • peachyring


  • james

    the animated gif fails, considering if you cover up the lines with your hand (ie the catalyst int he optical illusion part of things), you’ll notice the rise and fall of the triangle anyway. i’m sure it may be a proper illusion, but this gif fails in demonstrating that correctly.

  • Phil

    This actually has some practical application. I am investigating why reading putts on a golf green is unreliable, and this is the best demonstration of why. Now, If I can only figure out how to use this on the course.

  • Acolyte

    wow..Very nice

  • Akire

    The last one is clearly slanted. It didn’t even cross my mind that it was supposed to look horizontal.