This "right brain vs left brain test" from the Herald Sun is doing the rounds on the internet today. The article contains the so-called "spinning silhouette" optical illusion (below), and states that if you see the the dancer rotating in a clockwise direction "you use more of the right side of your brain and vice versa."
You've probably heard this left/ right brain dichotomy before. It goes something like this: the left hemisphere of the brain is logical, deductive, mathematical, etc., while the right hemisphere is artistic, visual and imaginative. The idea stems at least partly from the classic studies of split brain patients performed by Sperry and Gazzaniga in the 1960s.
There are some functional asymmetries in the brain, and it is true that certain regions of both hemispheres are specialized for particular functions. Speech illustrates this, but also shows that nothing is ever so simple when it comes to the brain: in most right-handed people, speech is processed in both hemispheres, but predominantly in the left. In some left-handers, speech is processed either predominantly in the right hemisphere or on both sides.
So the notion that someone is "left-brained" or "right-brained" is absolute nonsense. All complex behaviours and cognitive functions require the integrated actions of multiple brain regions in both hemispheres of the brain. All types of information are probably processed in both the left and right hemispheres (perhaps in different ways, so that the processing carried out on one side of the brain complements, rather than substitutes, that being carried out on the other).
When I first saw this illusion, I perceived the silhouette as spinning in a clockwise direction. But after staring at it for a while, it appeared to be rotating in the opposite direction. It took some time, but it happened eventually.
The effect can also be achieved by covering the silhouette and focusing on the shadow after you've looked at the illusion. When you uncover it, the image will suddenly appear to be rotating in the opposite direction.
Optical illusions can tell us much about the functioning of the brain's visual system. They work because the visual system reconstructs stimuli not according to how they actually are, but by making certain assumptions about their properties in order to "fill in the gaps".
It is unclear exactly how this illusion works, but it probably has something to do with the brain's representation of an ambiguous object. The silhouette is two-dimensional, but because almost all the objects we encounter are three-dimensional, the visual system reconstructs it as such. And the silhouette is not actually spinning - that is one of the assumptions made by the visual system. So, we perceive it as spinning in one direction one minute, and in the other the next.
Comments
In introductory psychology class, when I first saw the vase-faces example and read that we cannot see both at the same time, I studied the picture and then realized I could see both at the same time.
In your spinning silhouette, I can see it go either way. I can also see it as ambiguous so that I cannot say which way it's going.
I think some of what is assumed to be nature is the habit of the investigators.
Posted by: 6EQUJ5 | October 13, 2007 3:58 PM
I just finished Carl Sagan's The Dragons of Eden, which is about the evolution of intelligence, and the right/left brain differences are a major theme in most of the book. It was written thirty years ago, so I'm sure research on the subject has gone through many stages since then, but to me it is always interested to read opinions on science/medical issues from decades ago to see how accurate the early impressions of a phenomena were compared to what we know now. Sagan does a great job of explaining the function of the corpus callosum and other major structures in the brain, even though the book is out of date I think it's still a good read.
I actually first learned about the right/left brain differences when I took an art class in high school, the teacher emphasized "right brain exercises" for us.
By the way, that is a great optical illusion, and your tip about looking at the shadow really works!
Posted by: Anne-Marie | October 13, 2007 4:05 PM
Ah, it's just an excuse to look at a naked woman. Actually, I don't doubt the the right / left model is wildly over-simplified. (I loved The Dragons of Eden 30 years ago when it came out, by the way.) Still . . . I'm a poet & very "right brained" in the usual ways (Myers-Briggs INFJ) & my wife is an administrator & you'd call her "left brained" (M-B ISTJ). When I saw the image, I saw it as going clock-wise; when I showed it to my wife just now without telling her what it supposedly indicated, she saw it as going counter-clockwise. Just two data points, of course.
Posted by: jd | October 13, 2007 5:42 PM
I'm left-handed, and I saw the image as rotating counter-clockwise from the very beginning. Did n't seem clockwise at all. Don't know if that says anything.
Posted by: S | October 13, 2007 11:09 PM
In left-handers, speech is processed either predominantly in the right hemisphere or on both sides.
fwiw, speech is left-hemisphere lateralized in the great majority of left-handers. Right-hemisphere language lateralization is something like ~5% of the population, including both right and left handers.
I don't know how this illusion works, but I noticed that I can change my default direction of rotation by covering one eye and varying my angle of view with the uncovered eye, to favor exposure of its nasal vs. temporal retina to the stimulus, so I'm guessing works something like this: your brain extracts clockwise rotation in 3D from left-to-right movement across the 2D screen. A perception of left-to-right motion would be created by sequential stimulation of photoreceptors across the eyes, from nasal-to-temporal in the left eye and from temporal-to-nasal in the right eye. Projections from the nasal retina project mostly to the opposite hemisphere; projections from the temporal retina project mostly to the same hemisphere. In this ambiguous case, if you're perceiving clockwise rotation, input from the nasal retina of your left eye and the temporal retina of your right eye is being favored somehow such that it "wins" as being the part of your visual field that was stimulated "first" in the motion sequence. Where this favoring occurs, I don't know - it could be at the periphery, as photoreceptor density is higher in the nasal retina, or it could be central, such that the visual cortex on one side is resolving the input it gets from the eye faster than the on the other.
Now that I've bored everyone to death, if you can't get her to change directions, try the covering-one-eye thing.
Posted by: cerebrocrat | October 13, 2007 11:26 PM
#1 wrote:
"[...]when I first saw the vase-faces example and read that we cannot see both at the same time, I studied the picture and then realized I could see both at the same time."
Me, too. The same with the old woman/young woman picture and others.
"In your spinning silhouette, I can see it go either way. I can also see it as ambiguous so that I cannot say which way it's going."
The first rotation I saw it as rotating clockwise. The second rotation I saw it rotating CCW.
"I think some of what is assumed to be nature is the habit of the investigators."
And I expect everybody here knows what happens when you ass-u-me . . .
Posted by: Ronn! Blankenship | October 14, 2007 12:06 AM
As an artist, I have railed for years against the "left brain / right brain" myth. People are always trying to tell me how "right-brained" I am. Which I always find amusing since I work in software development. I have taken a number of these "tests" and gotten wildly varying results-- so much so that I have come to think of the whole thing as a little suspect.
There is a very popular book called "drawing on the right side of the brain," which was supposed to be a handbook for accessing the creativity of the right brain, with lots of exercises one can perform to increase right-brain activity.
I remember in art school we were actually assigned some of these exercises such as drawing with our left hands, because our left hand was connected to the right brain, which was supposed to be more creative ( I am right-handed). So, apparently, this was somehow supposed to lead to more "creative" work. And it did, after a fashion; but not because it stimulated the "creative side" of our brains. Using one's atypical hand forces one to slow down quite a bit, to concentrate more intensely on one's hand movement and mark making, and this is what changes the outcome. It is an interesting exercise, but I have never imagined for a moment that it's as directly related to brain hemisphere as it's made out to be.
I actually think it's a lot like the "horoscope effect": if you give someone a vaguely positive description of themselves, like "you are creative" or "you are analytical," they will tend to see themselves in that way and agree with you.
Posted by: eugene_X | October 14, 2007 3:13 AM
Interesting.
Initial I saw the rotation as clockwise but as you say if stare at the shadow it suddenly becomes counter clockwise. At that point I tried to switch back but couldn't till I scrolled the screen up so I could only see the foot I could then switch back to clockwise and then back again.
The eye covering trick didn't work for me?
Posted by: Nuytsia | October 14, 2007 6:54 AM
It's sort of a moving Necker cube. It's similar to the "trapezoidal window" illusion (google it).
By the way, someone mentioned the Myers-Briggs test -- it's even more unfounded than the right-brain/left-brain idea. It's more in the realm of horoscopes than science.
Posted by: J | October 14, 2007 10:39 AM
Here is how I can see it spinning in both directions. Try to make a point in the left side of the screen,than concentrate at that point, that you can see peripherically at the spinning
girl. Do the same think on the opposite side and see what happens. To me it worked also when i was reading the text under the spinning girl and looking peripherically at it. Don't know if works the same for you.
Posted by: James | October 14, 2007 3:25 PM
This may be weird, but I can see her switching directions without any "tricks" to try and make it happen. Sitting here with my wife I would say, she switched directions, but my wife would disagree. It is very weird.
Posted by: crossn81 | October 14, 2007 10:48 PM
The eye covering trick didn't work for me?
Did you do the nasal/temporal thing (looking at it with your peripheral vision on either side)? If so, and that didn't work, then I'm afraid we may have to consider the possibility that I'm full of shit.
Posted by: cerebrocrat | October 15, 2007 12:13 AM
I see the image spinning clockwise, so I am right brain, and thus not a logical person.
By the way, I am a software developer/business analyst.
There we go...
Posted by: Roland Hesz | October 15, 2007 10:37 AM
Enjoyed the article, and upon first seeing the image, it was rotating clockwise. I too was able to change perception by looking off to the left edge and observing peripherally. Was also able to get the image to alternate back and forth frontally, by alternating the observance first on the left edge and then with my vision centered on the image, then back to the left edge. The image didn't spin all the way around but alternated back and forth. Fun stuff for a neophyte.
Posted by: RDS | October 15, 2007 11:23 AM
Nice trick but upon page refresh, the image (nice, btw) begins spinning clockwise again, with the left foot planted (pivot foot.) After some time, the image changes direction with the right foot planted (new pivot foot.) It eventually switches back to the original rotation. Do a page refresh and it starts again. You can actually see where it transitions.
Interested in some Florida swamp land? :-}
Posted by: spinner | October 15, 2007 1:02 PM
I posted this over at my blog about a week ago and what was fascinating was the comments I got. Some people were just convinced it was a computer trick (just like commenter #15 here thinks). No matter how much evidence you present these people - even downloading the image to prove it's not a trick, they refuse to accept that their reality may not be as concrete as they think.
When the New Scientist came across this illusion and posted it on their blog they even pointed a link to my write up exclaiming how fascinating people reactions to the image are.
Though the illusion does not make a determination as to what "side" of your brain is dominant, it's the reaction people have to it that is the real science.
I remember reading years ago about someone who worked in the FBI (I think) and how they didn't actually rely that heavily on eye wittiness accounts of crimes. The problem law enforcement had was that two people can see the exact same thing but remember it differently. Too much of our own personality goes into how we choose to see the world and thus we create our own reality. Some wittinesses would become outraged that their testimony was doubted at all and even after seeing video footage of the crime would go as far as to say the footage had been doctored just to trick them.
It's interesting how convinced people are that their way of seeing the world is the only "correct" way. Just imagine what the world would be like if most people understood that they aren't always right and that their reality is a construct of what they choose to see and not see.
Teach people that lesson and religious, political and racial violence would disappear in no time.
Too bad it won't ever happen :(
Posted by: Dan Harlow | October 15, 2007 3:17 PM
I got something new here.
This is just fascinating: Look at the image and think about colors (which uses the right side of the brain). Imagine a big green screen for example. The image will rotate clockwise. Then make a calculum such as 4x7 or try to remember what you ate for breakfast (which uses the left side of the brain).
It worked pretty well for me. Please try this and tell us if you could control the shadow too. I'm very curious =)
Posted by: André Buitoni | October 15, 2007 11:35 PM
#16,
I accept that this is indeed interesting and that, upon further review, there is no obvious manipulation but in no way can I accept that it has the significance you attach to it.
First, however, it is a bit of a "computer trick" in that if you look at individual images, there are times when you can't tell if the model is facing towards or away from you. There is no definitive reference point at those times. This (reversing rotation) only works because the image is blacked out and would not work if brightly lit to the point where you would have visual reference points. Since Webster defines a trick as "a crafty procedure or practice meant to deceive or defraud," one could say the selective use of lack of physical reference is a trick. In that regard, this is not a naturally occurring phenomenon and therefore manipulated.
On your comments about seeing the world "only the 'correct' way," as an often bemused observer of American politics and popular culture, I can only say, "Shame on you" for doubting people that question what others portray as fact. Seems you're your own worst enemy on this point. People don't necessarily "choose" what they see and don't see. I saw the change in rotation but I questioned how it was done. That doesn't make me a harbinger of "religious, political and racial violence" as you imply.
Posted by: spinner | October 16, 2007 1:54 PM
I cannot see it going counter-clockwise AT ALL. I tried. I stared at it. The dancer is only going clockwise. I could never get those pictures-within-random-paintings thingies either.
Clockwise. Only clockwise.
Posted by: LLL | October 16, 2007 6:09 PM
I first saw the figure rotating anti-clockwise. If I concentrated on a hand of foot, the apparent rotation reversed. After that, the apparent rotation constantly switched. I am right-handed, if it matters
Posted by: Lyle G | October 16, 2007 8:55 PM
There are many ways to cause a reversal, Try moving the window to the bottom edge of the screen so only her head is showing and its pretty easy to get her to go back and forth.
Posted by: truth machine | October 17, 2007 10:47 AM
Just a quick observation:
Last night I showed my wife and 12-year-old daughter the spinning image. My daughter saw it change and it was insightful to have it change at different times for us. My wife, on the other hand, didn't see any change -- at all -- and was steadfastly defending her point of view to the point of getting mad about it. (Which explains volumes about our relationship.) ;)
Posted by: mod | October 17, 2007 5:17 PM
I don't know if you've tracked down the source of this particular silhouette illusion, but I think it's here:
http://www.procreo.jp/labo.html
Nobuyuki Kayahara (copyright 2003. Searching on the name produces previous cites to that person & website.
Oh, and subtle cues in the image (at the intersection points where occlusion of body parts should occur)can skew perception in favor of clockwise/counter clockwise. The versions drifting around might differ from the original.
bj
Posted by: bj | October 17, 2007 6:09 PM
She is naked!
Posted by: Desi | October 21, 2007 10:12 AM
I don't see what's so confusing about the illusion- it's simply a silloutte. At any moment, we could be looking at her from a given angle or 180 degrees from that angle. Thus the direction of rotation depends on whether your brain decides you're looking at her face or the back of her head. (or her left or right side, etc.)
I first saw her rotating clockwise... glancing at her feet sends it counter-clockwise. I can switch between by glancing around the image (staring at the feet works best) but I can't do it consciously.
Posted by: Abbie | October 21, 2007 6:42 PM
I can only make the image switch by thinking about it consciously - looking away and forcing myself to think about whether the leg would be sweeping in back or in front of the dancer as it moves from left to right if she were spinning counter-clockwise. Once I've figured out the correct way to perceive the leg-motion, I can more easily make myself do it in a few seconds.
Posted by: saurabh | October 22, 2007 1:09 AM
Well you posted this a few days ago.
I just discovered your blog. Didn't really take the time to read all the comments but, if you do answer, can you tell me why do I see two images,side by side, not mooving, right before it switches?
There's a good reason for that I'm sure. Still it feels strange.
Thanks and, I'll be back to this place.
Posted by: Gata | October 22, 2007 9:53 AM
Easy way to switch direction at will:
Clockwise: Start with your head over to the right edge of the screen. When her raised foot reaches the rightmost position, focus on her foot while you move your head to the left at a similar tracking speed to match the speed of her leg . You'll see her spinning clockwise.
For counterclockwise, move your head from left to right starting when her raised foot is at the leftmost position.
It can help to blink a bit to synchronize your vision to begin viewing at the extreme left and right foot positions. For further help, while your eyes are briefly closed in the blink, visualize the direction you want her to go.
Posted by: Buzz | October 24, 2007 10:42 PM
Try to imagine her lifted leg as right or left. If it is her right up then she will spin clockwise. If it is her left leg she will spin anti clockwise.
Posted by: Andrew Jeremijenko | October 25, 2007 11:15 AM
No matter what I try, she is only spinning clockwise. Does this mean half of my brain is missing??
Posted by: Sue | October 25, 2007 4:08 PM
I downloaded the image above and then did a bit of investigation and experimentation.
My apologies to Nobuyuki Kayahara (#23) but I used the image posted here which is an animated gif and not the original flash file.
Posted by: JGsez | October 25, 2007 5:39 PM
This is MY theory:
It’s just a shadow. You can’t really tell if the image is facing forward or backward, but since we are used to people looking at us, our first impression is that the dancer is looking at us. The dancer’s leg is moving left, stops, right, stops etc. If on the split-second your eyes saw the image, the dancer’s leg was moving left - you would think that she was spinning clockwise. If it was moving right - you would think that she was spinning counter-clockwise. From that point, your brain had already decided which direction the dancer was spinning and it would be very difficult to change your mind without looking away. It is NOT about whether you are logic or artistic, but the exact split-second your eyes first saw the image.
How’s my theory?
Posted by: Uri Kalish | October 28, 2007 6:03 PM
The reason you see her going both direction: http://www.shvoong.com/internet-and-technologies/1695919-optical-illusion-right-brain-left/
Posted by: Anonymous | October 29, 2007 3:13 AM
Okay, this illusion nearly broke my brain. I'm a bit dyslexic, but I didn't even think of that starting this article. I read the bit above the fold, and then looked at the image. It went clockwise. I couldn't get it to switch at all, even using the shadow-only technique described. Finally I tried the thing I do for all optical illusions, which is unfocus/cross my eyes until everything is about as blurry as possible. Then the image looked more like something swinging back and forth (or a downhill skier on moguls) instead of spinning. If I consciously thought of it as that, and then translated that motion to a thought of spinning either way, my brain seemed to latch onto that, and I could refocus and find it "spinning" the way I'd thought.
The first time I did it, and it went counter-clockwise, I hardly noticed. It still "felt" the same. This is the EXACT same feeling that happens when my dyslexia triggers. Because of that, I thought I'd misnomered the direction of spin to start with (due to dyslexia), not that my perception had flipped. I spent another agonizing minute trying to get it to flip again, this time making distinct mental notes as to which direction it was "spinning" both before and after. Finally it did, and this time, convinced I'd out-logic-ed my dyslexia, found it an amazing illusion.
AFAIK, dyslexia isn't linked with a right/left brain issue (that is, logic vs. emotion) but a much more literal left/right confusion. Is there any research that references dyslexia in regards to this sort of symmetrical illusion?
Posted by: Xepher | October 30, 2007 12:22 AM
By focussing on the doll's leg for 10s, I could see the change in the motion. So its all in mind?
Posted by: Animesh Sharma | October 30, 2007 7:23 AM
Curious, but explainable, (see Anonymous posting above)...Plus, some of you might be interested in 'This is Your Brain on Music' by D. Levaintin (may have spelt that last name wrong...), anywho, very interesting read, and a good compliment to 'The Immortal Game: A History of Chess'...Double-barrelled, ie. empiricism versus rationalism, splits the brain apart before it pulls it all together... Amygdala anyone???? Why, by the way, did you leave Wordpress? Cheers, c
Posted by: lindsay | October 30, 2007 8:38 AM
This is enthralling! I can watch her "switch" from side to side, but it looks as if she almost stops to do so. For me, thinking about which foot she is standing on (as previous commenter said) helps if you want her to change directions. Also, if I look away and come back, she always starts out as spinning clockwise. I'm left-handed, if that makes any difference.
Posted by: Heather | October 30, 2007 4:13 PM
Here's a better illustration of how the image was created:
http://gallery.krunk4ever.com/v/Animated_Gifs/all-spinning-dancer.gif.html
http://www.krunk4ever.com/blog/2007/10/17/spinning-dancer/
Posted by: Anonymous | October 30, 2007 5:51 PM
For me, making the image change directions is as easy as taking my left hand poining my index finger upward, I then rotate my hand either clock-wise or conter-clockwise.
Another note - For those of you who have trouble seeing the change at all, take you hand off your mouse. Or try moving the mouse to your left side.
Posted by: Victoria | November 10, 2007 12:49 PM
watch what it does when you just stare at it. Then look at it passively while you read. Focus on the words as you read and you can easily control it.
Posted by: jbshpu | December 13, 2007 11:48 PM
I can't see her as spinning any other way than clockwise, but I sort of expected that. I have such bad strabismus that the idea of binocular vision is basically foreign to me, and bad enough astigmatism in my left eye that it takes a great deal of effort to force it to focus well enough to read with it. I also have some dyslexia-like problems that cause me to continually misinterpret left-right orientations. (I don't seem to have the classic reversed letters thing when reading in English, but there are characters in two of my foreign languages that use non-Roman character sets that I can't tell apart. I have trouble with certain katakana, and I can't for the life of me distinguish between cursive Hebrew gimel and zayin, despite being able to read block/script Hebrew just fine. I also seem to be completely agnostic about English text direction, and didn't realise that text in a mirror was, well, mirror-imaged until I was 18 or so -- it looked just fine to me!)
To further compound the problem, I am right-handed primarily, but my left side is my stronger side, and I am pretty close to being ambidextrous (when I was first learning Hebrew, I wrote it better with my left hand than my right), and when I was little, I had what they call an "alternating dominant eye." I don't have that anymore because I'm visually impaired in my left eye. (You count that astigmatism in a very high number of diopters, such that if I had glasses, I'd have to get a monocle.)
So I'm kind of used to optical illusions not working really well for me...
Posted by: Interrobang | December 26, 2007 11:38 PM
I can get this to switch directions basically at will, but that's mostly because I trained myself to do that watching the end credits of every episode of Neon Genesis Evangelion (which features basically the same thing, only upside down).
Posted by: Andrew | December 27, 2007 3:00 PM
By telling myself "front, back" (referring to the raised leg) i can get her to rotate in either direction. If i tell myself "front, front" she faces me and swings her leg back and forth.
Posted by: Edward Emerson | February 6, 2008 9:53 AM
The right/left brain junk is not the only popular media theories of how the brain functions. For example: "the average person only uses 10% of their brain" or triune brain theory (reptilian brain, old and new mammalian brain). Every time I hear one of those things being spouted I want to rip my hair out, especially the latter since I wrote a nice term paper on it my senior year. Now my brain hurts.
Posted by: Chad | February 6, 2008 10:09 AM
Try this trick, moving your finger CC or Clockwise in front of the image, it changes every time for me, also, the difference of reading left to right, from right to left will change it (view the image scrolling your eyes ltr or rtl)..
Posted by: Ricardo | March 6, 2008 10:09 AM