VIDEO: Jastrow Illusion in Action


Take a look at this short and simple animated #gif showcasing the Jastrow illusion in action! The Jastrow illusion was first discovered in 1889, by American psychologist Joseph Jastrow. In this clip, both figures are identical in size, although the lower one appears to be slightly longer. The short edge of the upper shape is compared to the long side of the lower one. If you still can’t pinpoint what causes this illusion – it’s because the lower object is placed slightly to the right. This isn’t immediately noticed, because both of their edges are skewed, and both are placed along the imaginary line, one parallel to their edges. I’m not sure I managed to explain this properly, so better take a look at this picture below and you’ll understand the cause immediately!

  • z2d4th

    depending on the position, put that on the center and the length is the same.

  • Michael

    Yeah… sorry. Your image is bogus. The excuse could perhaps be because of skewed image by lens angle or whatever… but those two shapes absolutely do not fit.

    I get the illusion (it’s a clasic), but an animated GIF representation at an unrepresentative angle is a poor example.

    • destiny

      but they do that is why it is called an illusion!

    • rozziewoo

      how dare you!!! how could you do that, i think it’s brilliant!!! your so mean, you should crush people like that!!! disgrace!

    • rozziewoo

      i mean you SHOULDN’T HOW DARE YOU WHAT A DISAPPOINTMENT!!!!!!!!!!!!!!!!!!!!!!!!!

  • tienuien

    Haha! This trick was part of my magic box when I was a little child!

  • Phil

    That’s a pretty cool one

  • suor de sapo

    A classic, yet very effective!
    I think our brain lead us to compare the outer curve from B with the inner curve of A, obviously unfair…

  • themosayat

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  • Punisher

    I guess Vurdlak managed to explain it. When both the pieces are placed such that their left edge falls in a straight line , the illusion occurs as our brain compares lower edge of upper piece with upper edge of lower piece.

    However ,When the pieces are arranged such that the upper curves of both of them are parallel , and the corresponding corners fall on the same imaginary line ,they appear identical.

  • Annie

    It does work; I tried it with a piece of paper torn so that it was the same length as one of the shapes’ bottom lines…and the two were the same length.

  • carmenski

    when the piece is place on top it is at a lower level so it appears shorter, and below the strip it is higher so it appears larger,when it is on the strip it is slightly wider but not so much as you can tell. this my guess

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