Puff the Illusionary Dragon

By Neuroskeptic | September 18, 2009 9:46 am

There’s a lot of interest in visual illusions at the moment thanks to an excellent article over at Seed, This Picture Is Not Moving.

A while back I wrote about the Hollow Face Illusion in which a hollow (concave) mask of a face appears to be a solid (convex) face and I posted a seriously freaky video featuring Charlie Chaplin. But reader “Jake” just pointed out an even better example of the same illusion, the Paper Dragon.

See the video above. If you like what you see, you can make your own paper dragon by printing out this .pdf here. It only takes 10 minutes, scissors and a bit of sticky tape. I highly recommend it, the effect is astonishing – it really looks as though the dragon’s head is moving. You may need to close one eye to get the full experience. (The dragon was designed by ThinkFun).

The dragon, like the Charlie Chaplin mask, is an example of the “depth inversion” effect. Our visual system assumes that objects are convex, rather than concave, especially when those objects are familiar things like faces.

In my opinion the most interesting thing about the phenomena, and indeed with all illusions, is that concious belief cannot override the effect. I know that the dragon’s head is concave, I folded it up and stuck it together myself. Yet I still see it as convex. This is strong evidence for the modularity of mind. But that’s another story.

  • Anonymous

    If neuroscientists would really want to know more about the visual cortex they should self-experiment with some psychotropics.
    I can report a few funny experiences with Ibogaine some 12 years ago, though I would not recommend the stuff to everyone.

    The overall effects seem to clearly involve some progressive confusion of the “image building” mechanisms.

    – edges of fixed objects start to follow the edges of moving objects, like the contours of doors and furniture undulating in synch with the flame of a candle.

    – geometric patterns of lines, mostly triangular shapes, appearing on uniform surfaces like if the visual cortex WANTED to have some pattern instead of a dull space.

    – 3D volumes “sprouting” out of actual multicolored patterns (on a blanket) but returning to flatness when you try to touch them, apparently the tactile information being enough to fix the visual illusion.

    – very vivid general confusion about distance of objects but which, as above, is corrected by sensory information from other paths.

    – and, during the return to normal, a very strange effect of “frozen landscape”, the surroundings DO NOT change according to eyes or body movements like if the image were locked to the retina and suddenly after a fraction of second shift back where “they should be” with a white flash.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Mmm, interesting. I've no experience with psychedelics myself but I do take the antidepressant mirtazapine (Remeron), which has given me plenty of visuals (they don't tell you that on the packet).

    For one thing my dreams have been far more memorable, colourful, and elaborate than they ever were before – but even while awake there are visuals. Before I started on mirtazapine I basically never had visual mental imagery with eyes closed – I just saw coloured patches (mostly brown).

    Now, when I close my eyes, I see things. Especially when drifting off to sleep, but not only then. Actual things, not geometry. Landscapes and faces, mostly.

    It's a 5HT2A antagonist (amongst other things), but I read somewhere that it might have weak agonist activity. That would make sense because all classical psychedelics etc are 5HT2A agonists.

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    I have to say that I had never seen something original like this, because it's something really creative, and so much more because it's related to dragons.

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Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.


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