

Right brain vs Left brain - eposts
http://www.news.com.au/dailytelegraph/story/0,22049,22535838-5012895,00.html

======
amalcon
It's basically just badly rendered -- they have removed all depth clues
(lighting obviously, but they've also used flat projection instead of
perspective). Your brain fills it in by basically picking which side is in
front. That in turn determines the direction you see it rotating.

It's completely random, and has nothing to do with left or right brain
dominance; it's even easy to force it to switch to the other direction.

------
vlad
Here are some cool things about handedness.

We all 'know' that left-handers use their right brain and right-handers use
their left brain. In one library book about handedness, the author had found
studies about which parts of the brain are used by two groups of people, one
left-handed and one right-handed.

For right-handers, it was about 95% left-brain, and 5% right-brain. However,
for left-handers, there were three possibilities. It was about 60-65% right-
brain, 20-30% left-brain, and the cortex for 5 or 10% of them.

I don't remember what they were measuring, but a third option for left-handers
is interesting in itself. (It may have been a study about which eye is
dominant based on what a left-hander would say, so those for whom the cortex
functioned in a different way were grouped with left-handers?)

Another book says that in those people who 'hook' their wrist when they write
(so their hand is actually lower than their wrist), they do it subconsciously
because their wrong brain is being used. They are NOT meant to be using that
hand as their brain is struggling to use the correct brain. So, if you're
right-handed, and you hook, you might actually be right-brained and left-
handed. And, if you're 'left-handed' but you hook when you write, you're
actually a righty.

I thought about this a bit and noticed that with about 10% of people self-
identifying as left-handed, the stats above might fit. If 3-5 percent of
right-handers use their right-brain, maybe they 'hook' and are in fact natural
left-handers ('fake righties'). And if 20-30% of left-handers are actually
left-brained, then that's a few percent of the overall population who are
actually right-handed ('fake lefties'). Those could also be 'hookers' who
aren't actually using their natural hand.

------
whacked_new
This has been linkjacked to oblivion. And I have not seen any compelling
argument for right/left brainness based on viewing this image. It's merely an
illusion that plays with your depth perception from lack of contrast and depth
cues (motion parallax maybe, if you're so inclined).

I believe this is the _original_ source of the image.
<http://www.procreo.jp/labo/labo13.html> The author says nothing beyond it
being a mysterious illusion.

The switching is as arbitrary as the coriolis effect. Try this thought
experiment. Imagine instead of a woman, there was a perfect, black, sphere in
the image. You couldn't tell if it was rotating at all. Now I add a protrusion
to the "equator." Its length would vary in a sinusoidal fashion, and you could
guess the ball is rotating, but still cannot reason it's direction. I can then
successfully add protrusions such that it looks like a human and you wouldn't
be able to tell; it's a simple lack of visual cues.

edit: my bad, not the coriolis effect. I was referring to the toilet-draining
direction that is incorrectly attributed to the effect. The point is, given a
little push in one direction, the water, or the image, would continue to
rotate in that direction.

~~~
bluishgreen
"The switching is as arbitrary as the coriolis effect" - Why is the coriolis
effect arbitrary? I believe there are equations that predict both the
magnitude and the direction of deflection.

<http://en.wikipedia.org/wiki/Coriolis_effect>

~~~
whacked_new
My mistake, thanks for the correction.

------
jey
Neat illusion, but I wonder: is the whole left/right brain dominance idea
still considered valid by neuroscientists? I thought it was debunked.

~~~
dcurtis
It isn't really debunked. But this method of saying which side is "dominant"
is. Each eye's information is sent to the opposite hemisphere (edit: as well
as the corresponding hemisphere), so the idea is that if you see it moving
left, your right hemisphere is processing the information first, then your
left hemisphere.

But there is absolutely no conclusive evidence to suggest this is true, and to
show these kinds of things on The Daily Telegraph is a pretty big disservice
to teaching people about neuroscience, I think.

This doesn't mean there aren't differences in the hemispheres, but just that
visual tricks like this are probably not accurate at all for determining
hemisphere dominance (if such a thing exists).

~~~
whacked_new
<http://en.wikipedia.org/wiki/Optic_nerve>

Nerves of each eye are wired to both left and right brains. Hence there is no
order of processing information based on which field of view it is presented
in.

Curious discussion about hemispheric dominance; I never really thought about
it. I guess a better term is "lateralization."

~~~
dcurtis
That's true, but there is lateralization of the functions of vision. And the
speed of processing is the argument that I've heard used by people to describe
these visual phenomena.

------
dfranke
Either I'm so thoroughly one-side-brained that I can't comprehend any other
perspective, or we're all simply getting confused over semantics. I see the
woman turning to her right. Does anyone see otherwise? Whether you call that
clockwise or counter-clockwise just depends upon whether you define the
ceiling or the floor as the point of reference.

~~~
jey
Yes, you should be able to get it to spin the other way. Usually for something
like this to determine clockwise or counter-clockwise you imagine a clock
superimposed over the image from above, with the observer looking down at the
image and clock. Turning to her right would be clockwise.

~~~
dfranke
Nope, just can't see it. Maybe it's related to my inability to see
stereograms.

~~~
kirse
I too had trouble and it took me like 20 minutes, but I paid close attention
to the middle foot shadow and tried to imagine the tip of the foot going in
the direction I wanted.

After that I pretty much realized I can control reality with my perception!
(Heavy right-brainer here, apparently...)

------
juanpablo
I discovered that you can easily switch the rotation by:

A. Covering almost all the image and focusing only in the lower feet.

\- or -

B. Closing your eyes and trying to picture it rotating in the opposite
direction. And then opening your eyes.

------
henryw
that image is cool and freaky. it keeps switching on me. i think it has to
depend on what side of the brain you are using when you looking at the image.

------
kyro
Right brained here, apparently.

