Science, Art, Litt, Science based Art & Science Communication

The left brain/ right brain myth
Article by Neuroscience Department

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


My own words....

I'm left-handed,but trained into right-handed and I saw the image as rotating counter-clockwise from the very beginning. Didn't seem clockwise at all.

As I work in different fields, art , politics and software , I have railed for years against the "left brain / right brain" myth. People are always trying to tell me how "right or left -brained" I am. Which I always find amusing since I work in all fields with my heart and soul . 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...or the whole thing as totally suspecting and mind controlling or mind manipulating ....

For me: "The fact is that people are manipulated to believe since childhood what was written in the book years ago and it has become a fashion..

I remember in art school I was 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 and i smiled as i was trained to be right-handed though i now and then use my left hand). 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 typical 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. For me this left and right hand myth is a lot like the horoscope effect. if you give someone a vaguely positive description of themselves, like you are creative or what ever you tell them, they will tend to see themselves in that way and agree with you

You are what you want to believe and as a left handed person as a child and wastrained into right hand
I suspect in such things :)

In gratitude,
I am the onesoul

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Comment by AveHurley on August 23, 2009 at 5:52am
Wow ~ I was showing it to my son and suddenly he saw when it briefly went counter clockwise!! I then watched it longer and then saw it do a few counter clockwise movement~!! This really is neat. I like optical illustions~! I thought it was about the overall motion which goes clockwise but then seeing that little change in the lower right side when it switches back and forth to counter clockwise was really well done. I just didnt look at it long enough the first time.. :)Ave
Comment by AveHurley on August 23, 2009 at 5:44am
I'm sorry but I stared a long time at this and tried to see it counter clockwise in its progressions, but the artist who made this must have set it to demonstrate clockwise illusion. Some people however I have met, dont know their left from their right and even when tightening or loosening bolts will go in the opposite direction and have to later correct themselves. Perhaps some who see this only say counter clockwise because they misconstrue the illusion as to rotating the image on top towards the right and on the bottom it continues upside down appearing to rotate to the left~ I dont know all the scientific terms but think that maybe if a viewer thinks they are seeing it as rotating counter clockwise they are only mistaking it as they view it and see it clockwise but looking at the leg motions as it goes seeing the portion that appears to go from right to left and calling it counter clockwise~ :) Ave~
Comment by simple on August 15, 2009 at 10:35pm
"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."

--Yeah! someone gets it. The world is full of notions, isn't it? To some the glass is half empty/half full...

I see it both ways--and upside down, mirror image, but then I draw with both hands, sometimes at the same time.

So what does that say?

Sometimes I say it's a pain because I'm very visual and can get lost easily.
Comment by Dr. Krishna Kumari Challa on August 13, 2009 at 8:44am
A recent study shows It seems one side of the brain rearranges its neuronal circuits to replace the functions lost due to stroke ( The results were published in US journal of neuroscience ) According to the study although the right & left sides of the human brain have different functions, the unaffected side of stroke victims is capable of assuming the role of the damaged side & resume the activity patterns similar to those lost from the damaged sides!

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