What way do you see her spin?

I missed this last October, butaccording to the Herald-Sun (in what is till one of their most-emailed stories), whether you see the dancer spin clockwise or anticlockwise indicates which hemisphere of your brain is dominant. I’m curious as to which way Hoyden readers stack up, and whether the list of strengths for each matches your own perceptions of your mentalities.

Now, the Hun says that people can change the perceived direction of spin with a little bit of concentration, so what does that mean then? I started off seeing her spin clockwise, and it took me a while to reverse that spin. Now I can fairly reliably reverse the perceived direction of the spin any time I choose with the old magic-eye squinting defocussing trick. How about you lot? Go and give it a try before reading the rest of this story.

If you find that you too can actually reverse the spin easily with a bit of practise, I’m not at all surprised. This illusion in truth has nothing at all to do with any cerebral-hemisphere-dominance, the whole right-brain left-brain theory being crock: a gross oversimplification and unjustified extrapolation of results from studying so-called “split-brain” patients who had had their cross-hemispheric connections (via the corpus callosum) surgically severed.

So how does the illusion work? Maria Brumm at Gabbro B-sides explains:

This much is true: you process some visual stimuli on the right side of your brain, and some on the left. You also have two optic nerves, one from the back of each eyeball. On their way to the brain these nerves meet up in a location called the optic chiasm. From the optic chiasm, information about the left side of your field of view, no matter which eye it’s coming from, is sent to the right hemisphere of your brain to be processed. Information about the right side of your field of view is sent to the left hemisphere. Therefore, if you want to see what your right brain makes of the dancer, you just need to look over to her right and watch her from your peripheral vision. Looking to her left will show you the left-brained view.

After a little practice, I can get the dancer to switch between clockwise and counter-clockwise spins – from either side of my visual field. This means both sides of my brain see both directions of spin just fine. This effect doesn’t have anything to do with differences in visual processing by the right and left sides of the brain.

Actually, the spinning dancer is an example of something called bistable perception. As an object that can be seen in either of two ways, it’s in the same class of illusion as the Necker cube and the face-vase.

There’s more to learn about bistable perception and optical illusions in Maria’s post, particularly if you follow the links she’s embedded which I haven’t included in the above quote.

Via Maria, I also learned that the silhouette illusion was created by Nobuyuki Kayahara, which is more than the Hun saw fit to tell anyone.

Categories: fun & hobbies, media, skepticism


19 replies

  1. This is very cool. I saw her spin counter-clockwise for the first few seconds, then clockwise for ages, before being able to get her to change. I can’t quite get her to change on demand yet, but it happens after a few tries.

  2. Clockwise for me (just clockwise).

  3. Started off clockwise, but changed to anti-clockwise with a bit of concentration. Can now choose. I think it may have something to do with where the outstretched leg is when you first look at it. I found I was inclined to assume the leg was spinning towards me, which determined the perceived direction of rotation for the rest of the image.

  4. Started out anti-clockwise, then switched to clockwise. Very cool.

  5. I meant to add that according to the list of traits, I’m somewhat more left brained. It’s hard to say, because I have a lot of traits from both lists.

  6. This is completely baffling to me, even after the explanation. I can make her spin anti-clockwise only by squinting at her from the left-hand side of my vision, turning my head almost completely away to achieve this. As soon as I start to move my head back towards the middle she switches to clockwise again. I wouldn’t have believed it.
    M-H’s last blog post..It’s official

  7. I thought that It Had Been Determined that it’s simply hard coded to change direction.
    MatildaZQ’s last blog post..Le manchot est mort, Vive le manchot: Eugene Onegin at Lyric Opera

  8. Both.
    No disrespect intended but animated gifs such as this one can have embedded commands to to loop (forward/backward) for a series of frames. There are 34 frames for a complete rotation for this gif, which could be set up for a continuous loop (clockwise) for x amount of times followed by a reversal (counterclockwise) for x times, and so forth. Or it was set for a random x set.
    Then again, perhaps I’m over thinking it. : )
    Becki Jayne’s last blog post..Marc Rudov’s sexist problem

  9. I concede the possibility that both Becki Jayne and Matilda ZQ have pointed out, that the animation is programmed to flip.
    Two responses:
    * if so, then that only debunks the purported left-brain right-brain association even harder
    * BUT what about the various people who can’t make the perceived spin flip no matter how hard they try? Or where two people are simultaneously looking at the image on the same monitor, and perceiving the spin differently? (like my son and I just now)
    Certainly I see the animation stutter at times, but that’s not when the image flips for me. I’m not at all convinced that there are flips programmed in.
    BTW, this morning my default perception was clockwise, then I had a period where the perception was arbitrary as I checked back in on this thread after lunchtime, and I could flip it at ease. Now in late arvo my default perception is counter-clockwise, and I can’t flip it. Perhaps my eyes are getting tired.

  10. Yup, my boyfriend and I were both watching it just now, and while we both saw it as clockwise initially, his vision flipped to counter-clockwise, while mine remained the clockwise.

  11. Dang, from the title I thought this was going to be about Hillary Clinton.
    Oh, clockwise for me and I can’t make it reverse.

  12. Anti-clockwise, then shifting to clockwise if I focus on the left side of the image. The Bloke here says it’s definitely clockwise and unshifting.
    We’ve both got rotten eyesight, incidentally, but different kinds.

  13. at first, counterclockwise. then i scrolled the page a little, and when i looked back, it was clockwise. then i stared at it for a few moments and it went back to counterclockwise. then i blinked and it went back to clockwise. now i’m just dizzy.
    also, for the record, when i first saw the title of the post, i thought it was about her stereotypically barbie-esque body silhouette. 🙂
    ladoctorita’s last blog post..stupid link of the day

  14. I simply *cannot* get it to switch – it’s always clockwise. It’s really annoying me – I was like that with those damn magic eye pictures as well (like the guy out of Mallrats!) but eventually cracked it. Maybe I’ll get there in the end. Until then, I will have to live with failure.
    Katie Lee’s last blog post..Dollymix’s interview with Jacqui Smith, the UK’s first female Home Secretary

  15. But why is the dancer naked?

  16. And now I notice that if I scroll down to where only her head is visible she is going counter-clockwise, and as I slowly scroll down she flips at about the point that her breasts slip into view. Every time.
    M-H’s last blog post..It’s official

  17. For me it seems that the decision to perceive it as clockwise or anticlockwise occurs when her head is seen from the back. So perhaps when her head is first seen in profile the perception of anticlockwise or clockwise is locked in depending on which profile you are first presented with? If there is a preference for seeing the face as rotating towards you then a right profile will be seen as clockwise rotation, a left as anti.

  18. Anti-clockwise all the time, very clearly.

  19. su
    since I seem to have the best luck switching which way I see her spinning when I glance away right before her front/back is facing me, I think you may be onto something.
    Mickle’s last blog post..Why I Hate Local News

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