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By on December 27, 2011, with 41 Comments

Tracheal Tube Optical IllusionThe tracheal tube illusion animation your about to see has been circulating the net lately. It is a simple relative sizes optical illusion, which goes in tandem with the following question:

Which tracheal tube is longer?

When I first saw it, two questions immediately captured my attention: A) What is “tracheal tube”? and B) Will the illusion work for others, where I wasn’t even sure it worked for me. Still, based on its popularity on the various social networks (=read: Facebook), I suppose it is OK.

So, not being lazy, I have searched the web and learned that tracheal tube is a catheter (?!) that can be inserted into the patient’s trachea in order to establish and maintain clear airway

Never would’ve guessed the day will come when we would have catheter illusions appearing on this site! It would probably be the last thing I could come up with, if someone asked me in prior to give my wildest prediction regarding future illusion submissions! In this illusion the lower tube should appear longer when positioned vertically… What do you think of it?

Tracheal Tube Optical Illusion


41 Responses
  1. Tiffani says:

    The only thing about optical illusions like this one is that I’ve seen so many that now whenever I see the question “Which one is longer?” I automatically say, “They’s the same length.”

    • Dolphin says:

      I agree with Tiffani… After a while (I started liking optical illusions at like 8, so I’ve had plenty of time to see the patterns of it) I started doing that,too.
      Anyways, it’s still a good illusion.

  2. me123987645 says:

    To me, the bottom one looks a tad bit longer than the top.

  3. Dallen49 says:

    I think its very clever. The Vertical tube made me look at the horizontal as two smaller tubes instead of one tube the same size as the vertical.

  4. Larry says:

    Me thinks the illusion was ruined by firstly demonstrating the vertical tube is the same length with the animation demonstrating same.

  5. Chakolate says:

    I’ve been told (I don’t know if it’s true) that the vertical tube seems longer because of the shape of our eyelids. Anything vertical takes up more of the range of vision than the same length seen horizontally. In other words, our peripheral vision lets the horizontal bar take up less of the field of vision, but a vertical bar fills more of it.

    I hope that makes sense?

  6. quack yup quack says:

    yaya ya i know pretty much seen it ina different version i think even in this web site
    and 1st? hope so

  7. eee efff geee says:

    Let me guess……..*GASP* THERE BOTH THE SAME SIZE???? wow…..who knew.

  8. Glendalough says:

    I’ve seen so very many of these there is no longer a question in my mind about length/shape/whatever. Or am I just kidding myself and ignoring the illusion completely??

  9. Glendalough says:

    Object resembles a vacuum cleaner tube, not an endotracheal tube.

  10. MrEd says:

    I like these kind of illusions, I have one small request, can we put the animated gif inside the page and not direclty in the iGoogle widget, the resons:
    1: it spoils the illusion.
    2: is very distracting and some people like to keep the page open.

  11. Sergio Ramos says:

    only seems longer in the T form because the top point of the vertical tube seems to be “extended” due too the color of the adjacent corresponding tube. if you were to look lower too the vertical tube and see the image with your peripheral vision. you would see it more of the same length. but focusing on the vertical tube in the mid to high area (more so mid) causes the tube to seem longer. possibly due to the fact that the optic nerve in a way is still much like a compound eye in that it has, i guess you can call it, a pixelated surface and cant perfectly, smoothly, transition light between what gaps there are in the optic nerve.

    kinda the same “phenomenon” that happens when you stare at a dot on a paper and close in on it with another dot just off too the side, the extra dot disappears into a blind spot. probably due too the gaps in the “pixels”(?) in the optic nerve.

    my theory at least o.o

  12. NeeL says:

    I think there are too many details on the catheter, for it to work properly. Or maybe you have trained my eye for this.

    For stereotypical purposes, I’ll suggest that this illusion comes from the United States of America. Because a catheter is in their culture most likely a more common thing then in other countries. :)

    Forget the stereotype I was going for, it’s a fact: http://www.nationmaster.com/graph/hea_obe-health-obesity

    • tom says:

      @NeeL … it’s a breathing tube, usually inserted by anesthesiologists in the operating room … what does that have to do with obesity? … take your America-bashing elsewhere

  13. sage says:

    They look like “about” the same size to me. I suppose the vertical one should be the one expected to appear longer, but I’m not even sure !

  14. Kimon says:

    It does look longer when perpendicular.

  15. Nisheeth says:

    It does appear longer… when I squint my eyes and look at it sideways…

  16. Philippe says:

    Actually, it’s a long-time well-known illusion. Most of objects, if not all of them, seem longer when positioned vertically than when positionned horizontally. :-)

  17. Patrick says:

    they are exactely the same and it is in the coulor that make the difference. Good one

  18. Louise says:

    Maybe it’s a personal thing this one. Not as good as most of the illusions. Some people have better spacial awareness. The illusion doesn’t work for me personally, they look the same size either way.

  19. Louise says:

    *spatial awareness even :D

  20. Victoria says:

    They appeared the same length to me!

  21. leperchaun says:

    When the lower tube is vertical it looks longer but its not.

  22. GEM says:

    I’ve seen it before. Quite good they are the same size but your brain tells you the vertical one is longer. Great Job :)

  23. robert says:

    This is actually really easy to explain. The “illusion” is not that the actual tube grow it’s that the size of the frame grows. To verify this, take two pictures, first take one where it’s in the “T” formation. Then cut the picture right at the bottom of the vertical tube to the top of the same tube. Take that picture into something like MS Paint along with a picture of the original horizontal image. When you flip the vertical tube horizontal you’ll see that the picture is the same size. The “illusion” is that the eye adds in the extra height necessary to accommodate the horizontal tube and therefore your eye thinks it’s longer than it is. Another way to show this is make the white box that the image is rotating in perfectly square accommodating the side by side and the “T” configurations. You’ll quickly lose the appearance of added height.

  24. PromiseMe says:

    I think the animation goes too fast for it to work ._.

  25. Anonymous says:

    I agree

  26. J.M.E. says:

    This does not add up.
    When measured directly on the screen the vertical IS about 7 m.m. longer than the horisontal!!!
    Try for yourself. Disapointing.
    What’s the meaning of posting this?
    Just wondering!?

  27. Valerie says:

    No don’t see the difference. They both look the same size to me.

  28. Cheynelle says:

    It’s not an optical illusion. If you measure the vertical tube and the horizontal one, they are different sizes.

  29. Aron Rubin says:

    I am not sure I understand the helicopter link. In this case it seems less of perspective and more like the brain adds the diameter of the upper tube to the length of the lower tube when it is displayed together. This has happened to me before when creating custom typography.

  30. julia belle says:

    yay i got the first comment at first i know that they were the same size

  31. Flabawoogl says:

    When I saw this on my iGoogle app, I took awhile to get.

  32. Nitin says:

    This one’s a scam… measured the vertical one. It is longer than the other. It just gets shortened as it rotates to a horizontal position.

  33. Tsaukpaetra says:

    Interesting. I bet that if the lower tube simply swiveled down, the effect would be lost…

  34. Sarah says:

    Da Hora !

  35. the man says:

    does anyone else notice that the top tube changes size in the middle of the action and also look at how one tube is thinner than the other in the two pictures next to each other

  36. This is why says:

    This is the reason we have Widescreen :)

  37. Alice Alexander says:

    There is a distance, the width of the horizontal tube, which is added to the length of the vertitical tube, making it appear longer. Overlap the horizontal tube with the point of the vertical, rather than just allowing a touch.

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