Which way does the dancer spin?

[MacDoc]

Then how do you explain the differences in perception amongst a group.
Some people can ONLY perceive one direction of rotation - others switch easily.

What I found amusing was that those that saw counterclockwise INSISTED they were seeing it the "correct" way....

facts rule ..hmmmmm

[DaveD]

The real trick is not in the animation, which is just an optical illusion, but in the lists of attributes. They're so evenly spread they could have been written by an astrologer.

[MacDoc]

It's called a gradient and we are most of us a mix between the two aspects.

Our personality can be thought of as a result of the degree to which these left and right brains interact, or, in some cases, do not interact. It is a simplification to identify "left brain" types who are very analytical and orderly. We likewise certainly know of the artistic, unpredictability and creativity of "right brain" types. But each of us draws upon specific sides of our brain for a variety of daily functions, depending on such things as our age, education and life experiences. The choices of which brain is in control of which situations is what forges our personalities and determines our character.

Experiments show that most children rank highly creative (right brain) before entering school. Because our educational systems place a higher value on left brain skills such as mathematics, logic and language than it does on drawing or using our imagination, only ten percent of these same children will rank highly creative by age 7. By the time we are adults, high creativity remains in only 2 percent of the population.

There are low % types on both sides and some very few that just have to cover one eye to switch entirely.

It's no different than handedness most can train themsleves to reduce the imbalance and some are naturally balanced.
It's not a trick - it's an observed phenomena with underpinnings in brain diversity.

[DGMontgomery]

Flipping back and forth, and it makes me feel strange when I try to make the side-by side images go in opposite directions.

I like it.

[DavidMcC]

the dancer must be backlit to be in silhouette and so it makes sense that the raised leg is further from you when you can see the shadow.

No, it does not make sense. There is no logically correct way to see the silhouette/shadow, raised leg or no raised leg.

[Geraint]

Maybe. And as someone's pointed out, it could equally well be a reflection.

[Horwood Beer-Master]

Although I’ve got the hang of getting the direction to ‘change’ in my mind I can’t get both to spin the same way. When I see the direction change for one it automatically changes for the other, I think it’s because my brain assumes one is a mirror image of the other.

Would it be at all possible to get an image like this but with the dancers out of synch with each other in order to break the ‘mirror’ illusion.

[DavidMcC]

That's odd, I've suddenly started seeing one going clockwise and the other anticlockwise, regardless of which version of the image I see, and they frequently switch directions. Until now, they all went clockwise all the time. I don't know whether it had anything to do with seeing the bottom of the image truncated by the screen temporarily.

[MacDoc]

I suspect it might have to do with time of day and level of relaxation as well as surrounding images.

If you cover one image or the other there is different effects as well....

When they are NOT rotating for me - but going back and forth 180 degrees perceived, covering one almost immediately triggers sense of 360 rotation.

Brains are strange...

Have not tried with one eye or the other - that too should have some bearing.

I'd like to hear from any left handed people too.

[MacDoc]

Okay this set is following the same sequence ( not reversed ) but slightly out of synch over time.

Good learning curve for me

oh that's kind freaky as it shifts direction

If you cross your eyes you get a 3rd dancer or perhaps an overlay of the two - further phenomena.

If you populate the screen with multiples of in synch and out of synch pairs it's even stranger

[Homo Incredulous]

I'm left handed, and I could only see the image going clockwise when it was on its own.
With the two images together, I can make the left-hand one change direction, but I cannot make the right-hand one do so. She is still only turning clockwise.
I don't feel at all characterised by the "right-brain" list of attributes, by the way.

[MacDoc]

It's all on a bell curve and I'm sure your handedness has some impact on the dominance character, it might even offset the "norm" established for right handers. Again it's a curve so there are certain aspects for me that glare and I could NOT reverse the orginal single image period tho they do reverse when presented out of synch for me.

The actual aspects of right or left brain is reasonably well established by those few unfortunates that have had their left and right hemispheres physically separated for medical reasons.

It's quite spooky.

How that plays out in each individual is far from clear.

We know some people are more musical than others....and that there is a genetic bias. Some better at math, some at visualization etc. .....the details of that for each individual is far from clear

It depends on the where you are on the bell curve and I also suspect there are diurnal and attentive aspects - ie - I find more reversal when the figures are not focused on but are peripheral.

[DavidMcC]

I see she's reached the New Scientist, and caused a stir on their blog! Someone even claims to understand why she's "going counter-clockwise, always"!
Bring on the dancing girl

OK, hands up if you can make her change direction. No? Only clockwise? How about making her stop?

This strangely compelling, animated silhouette of a woman spinning gracefully has been doing the rounds via email lately and the New Scientist office was one of many that spent a guiltily non-productive afternoon staring at her.

Why? Because some people see her spinning clockwise, some see her moving counterclockwise, and most, if they stare long enough, see her switch direction. Some can make her change at will. But no-one, it seems, can make her move in two directions at once.

All pretty spooky since she is an unchanging animation of only 34 frames in a constant loop. What seems to be happening is that the two-dimensional image does not contain enough three-dimensional information to tell the brain which way she is spinning. So your brain helpfully fills this in, as brains do in many optical illusions. Only, in this case the brain can do it one of two ways.

How about the stopping? Well, perception of time is pretty subjective, and our experience of inertia is that when things make a 180-degree change in direction, they have to slow and stop first.

What this animation does not involve is different sides of the brain, as the initial post claims. What you see is purely due to your perceptual and cognitive flexibility.

What is a little scary is how threatened by this some people clearly feel. The blogosphere is rife with arguments and ingenious explanations of the lady, with some people simply refusing to believe it isn’t an animation tick that really changes direction every few minutes.

Even more common are the people who are sure they know how to make her change direction. According to them, the trick is to hold your head or hands in certain ways, tilt the screen or look at her out of the corner of one eye. It was what they were doing when they saw her change – so it must work. Right?

Debora Mackenzie, New Scientist contributor

It's clear that the optical illusions involved don't give any reliable information about which side of the brain you use most!

[MacDoc]

It's clear that the optical illusions involved don't give any reliable information about which side of the brain you use most!

How ever did you draw that conclusion from the post you provided?

Because some people see her spinning clockwise, some see her moving counterclockwise, and most, if they stare long enough, see her switch direction. Some can make her change at will.

Sounds to me like a classic bell curve.
Are you providing an alternative explanation why she apparently spins one way for some and the other way for others????
••

I sent the link to this thread and the altered gifs to the New Scientist author. We'll see if she responds.

[Astaroth]

MacDoc, you are committing a huge fallacy here. This is your reasoning:

1. One of the many ways of splitting people into two groups is the right/left brain thing.
2. There is an optical illusion which can be viewed in two ways.
3. Some people see mostly one way, other people see mostly the other. People are split into two groups by this.
4. Hence, the way you see the illusion is connected to the right/left brain thing.

Need I go on?

[eatapc]

I sent the link to this thread and the altered gifs to the New Scientist author. We'll see if she responds.

MacDoc, you are committing a huge fallacy here....

I googled the spinning dancer illusion all morning, and this forum has one of the few threads with even a remotely intelligent discussion about it. As a Dawkins fan, I was happy to discover this site.

The spinning dancer created quite a stir at work a few days ago. About a dozen of us gathered around to watch it, calling out what we were seeing. I saw counterclockwise only. One coworker (gay, outgoing, touchy-feely, etc.) saw only clockwise spinning (and was upset about it). Most saw it switching, but usually with one direction or the other dominating. Even with us calling out our own directions, we couldn't get anyone to "sync up" with anyone else for more than a few seconds.

Like MacDoc, I captured the animation, then fooled around with it in Final Cut Pro, flopping it and making it run in reverse. It's a fascinating illusion. I've read a few explanations for why it works, but the fact that this illusion reveals consistent differences in a wide range of observers gives it potency beyond the usual "gestalt switch" tricks. Maybe it does reveal fundamental brain differences. The left brain versus right brain explanation has made it popular and given it viral power, but I'm skeptical. However, to echo MacDoc, is there a better theory?

[FedUpWithFaith]

Unless I see some pMRI data that correlates particular brain differences to different perceptions of the rotation I will remain skeptical, though the idea of left-brain, right-brain differences with respect to this issue certainly seems plausible.

[Astaroth]

The right/left brain connection is NOT a theory. It is based on nothing but the fallacy I described above, there IS no connection. Therefore, you can't even ask "is there a better theory?". Come up with one first.

[MacDoc]

MacDoc, you are committing a huge fallacy here. This is your reasoning:

1. One of the many ways of splitting people into two groups is the right/left brain thing.
2. There is an optical illusion which can be viewed in two ways.
3. Some people see mostly one way, other people see mostly the other. People are split into two groups by this.
4. Hence, the way you see the illusion is connected to the right/left brain thing.

Need I go on?

Yes you do because you err.

In this situation people are spread over a bell curve as they are with right and left brain dominance - it's not an either or.

That some switch easier is clue that it may be related to dominant brain as we know the two sides process differently and we know there is a range of dominance within the general population.

You might as well say about any optical illusion that it has no dependency on our physiology.

A correlation is not proof - it IS evidence to be explored further.
The ARTICLE, not me, implied that there was some research underpinnings to this.

By altering the images I tried to remove some potential bias of a flawed image and see what different results cropped up.

One must accept differential capabilities between hemispheres ( proven ),
One must also accept a spread of dominance of one hemisphere or the other in the human population ( may be arguable but I suspect it's pretty solid ).

At this point I'd be happy to hear another hypothesis - which is all this is - to explain the bell curve results across the population....which is likely what the underlying source found.

If you present this to a population a certain percentage will not see the number embedded.

In this case correlation has underlying physical proof so is not a hypothesis.

I'm all ears on the alternative hypothesis for why the population variance in the case of perceived rotation and ability to switch between them.??

'Til then we'll enjoy the phenomena and await your alternative explanation.

In the meantime those who are interested in the hypothesis, they might try and correlate THIS test with the purported visual test.

http://www.web-us.com/brain/braindominance.htm

My results

You responded as a right brained person to 15 questions, and you responded as a left brained person to 3 questions.

I'm also

I'm in the less numerous part of the population that uses the right side of the brain the most, it's very difficult for me to see the dancer spinning anti-clockwise -

One correlation....anyone else.

[Astaroth]

I don't even know where to start. This is a waste of time, enjoy.

[eatapc]

I don't even know where to start. This is a waste of time, enjoy.

Astaroth, you can't present an invalid deductive syllogism as proof that this is a fallacy rather than a theory. Scientists typically use inductive reasoning to develop theories that must be tested empirically, but theories are never proven. Any theory can be turned into an invalid syllogism. Empiricism, not logic, is how you falsify a theory like this.

I really would like to hear a scientific explanation for the phenomenon. The first step for lay people like me might be to test for a correlation between spinning direction and ocular dominance. http://en.wikipedia.org/wiki/Ocular_dominance

Unscientifically, all of us at work thought the observed direction of the spin was a good predictor of personality type: the rational/verbal types saw counterclockwise while the intuitive/artsy types saw clockwise. That doesn't mean much, but it did make me think it would be interesting to look into it.

[MacDoc]

Exactly.
The "test" did not arise out of nowhere.
It was PRESENTED as a left right dominance indicator.

If you have an alternative explanation for the population variance in observation Asteroth let's hear it, otherwise your retreat to high dudgeon is noted and dismissed.

••••

eatapc - I think there should be an right eye left eye aspect but I wonder if we perceive the rotation correctly without binocular vision and that may actually be the determining factor - which vision channel dominates between the two.
Some observation to that affect is people have reported seeing it switch in their peripheral vision. I've noticed that as well when the spinning images are not really occupying my attention.
Might be attention, might be which eye.
Interesting what a few on off pixels can elicit.

•••

Some of the reactions and indignant insistence on"one direction only" are hilarious.

http://www.metafilter.com/65382/Silhouette-pirouette

Good cross section.
Fun with science.

[Astaroth]

Mac, I saw this illusion many many months ago in a different context and it was not presented as a right/left brain test, it was presented as an optical illusion and nothing more. You are making a false correlation and you have almost zero reason to be doing that. I hope you eventually realize it.

[DavidMcC]

I agree with Astaroth. This optical illusion may tell us something about how our visual cortex works (making a 3-D model of what the compressed visual data sent by the eyes seem to represent, guessing at details that can't be seen directly in the image, ambiguous in this case, as it is a very sketchy, 2-D image of something assumed to be 3-D), but why the rest of the brain? Surely, we are not using our entire brain when looking at the dancer.

[eatapc]

Mac, I saw this illusion many many months ago in a different context and it was not presented as a right/left brain test....

True. I think I conceded that in my first post. Someone somewhere (perhaps a blogger?) made a brain dominance supposition about it, and the illusion suddenly became a viral hit, getting picked up by mainstream media.

You are making a false correlation and you have almost zero reason to be doing that.

I'd like to know who first made the correlation. It may turn out to be total nonsense, but it was a brilliant idea for two reasons: 1) It sparked the popular imagination and made the illusion much more interesting; 2) There may be something to it.

I'd call it fringe science as opposed to pseudoscience. As I said, I tried it on a dozen people at work, and the admittedly anecdotal results did not falsify the theory. My left brain remains skeptical about it, but my right brain wants to believe.

Surely, we are not using our entire brain when looking at the dancer.

We certainly are. From an article in "The New Scientist" by John McCrone: "...in a test in which split-brain patients had to match a series of household objects, the left brain would match by function while the right would match by appearance. So, when seeing a cake on a plate, the left brain would connect to a picture of a fork and spoon while the right brain would select a picture of a broad-brimmed hat. ...brain-scanning experiments began to show that both sides of the brain played an active role in such processes." http://www.rense.com/general2/rb.htm