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http://www.abc.net.au/catalyst/stories/s1063853.htm

Australian neuro-scientist, Jack Pettigrew believes it’s all to do with how
their brains switch from one side to the other. Jonica Newby’s fascinating
report follows Jack’s personal and scientific journey deep into the functioning
of the brain. It’s lead him to question the very nature of how our brains work.
Along the way viewers will be able to work out how quickly their brains switch
from left to right hemisphere. According to Pettigrew, this brain switching
speed could determine what we’ll be good at in life.
2) You will firstly need to view the test, known as Bonneh's
Illusion, here
http://www.uq.edu.au/nuq/jack/bonneh.html
Then follow these modified instructions:
Get a pen and paper
Get a friend to time the test for 30 seconds.
When your friend says go, concentrate on the top left yellow dot. As
you stare at this dot, the other dots will begin to disappear. Each time
all three dots re-appear, tick the paper.
Your friend should call stop after 30 seconds.
SCORES:
If you scored between 4 and 6, your brain switch rate is average.
If you scored more than 6, your brains switch rate is fast, like a dancer.
If you scored less than 4, your brain switch rate is slow, like a
mathematicians.
(full transcript...)
http://www.uq.edu.au/nuq/jack/bonneh.html
Bonneh's Illusion (Motion-Induced Blindness).
We have been working on this striking illusion that was discovered by Yoram
Bonneh. There are a number of similarities to rivalry.
Look steadily at one stationary point, such as one of the yellow discs, as
blinks and sudden eye movements destroy the illusion Notice that one, two or all
of the yellow discs will disppear and reappear.
We can make the disappearing yellow dots reappear by disrupting the activity
of the left hemisphere using TMS. Alternatively, we can increase the duration of
the disappearance by disrupting teh activity of the Right hemsiphere with
precisely time pulses (the Right hemisphere seems to be much more picky about
the prcise timing of teh TMS pulse thanthe Left, perhasp associated with the
large blocks of time that the Left deals in ).
Our interpretation is that the left hemisphere is "into denial" as Ramachandran
showed so nicely ( in patients suffering from right hemisphere damage, who felt
less compelled to deny their paralysis when right hemisphere function was
temporarily improved by caloric stimulation).
If we are correct, the illusion and perceptual rivalry may share the same
competitive tussle between the right and left sides of the brain. The
disappearance of the yellow discs may thus represent the ascendancy of the Left,
while their reappearance may represent the ascendancy of the Right.
Critics have pointed out that there is only one Left hemisphere while there are
a number of different possible patterns of disappearance of the yellow discs (8
to be precise). This may be a little pedantic , since all of these patterns can
be subsumed under one rubric, viz:- disappearance. We are presently working on
multi-stable perceptions where more than two alternatives are possible. These do
not seem to present fatal difficulties to the hemispheric switching idea so far.
In any case, multistable rivalries are relatively rare compared to the vast
majority of rivalries, which are bistable.
Another apparent difference between binocular rivalry and Bonneh's MIB is that
increasing the contrast seems to increase the duration of the dominant phase in
opposite directions, since brighter yellow dots increase the disappearance phase
while increasing contrast shortens the suppressed phase but has not effect on
the dominant phase of binocular rivalry. We think that it is premature to make
too much of this difference, since there are some forms of stimulus manipulation
(e.g. changing the context) that CAN increase the dominance phase duration in
binocular rivalry. The more monophasic form of the oscillation in Bonneh's MIB
might align it more apporpriately with only one phase of the binocular rivalry
oscillation, for example. In addition, brightening the yellow discs might be
seen as a contextual stimulus in the sense that this would further
separate the blue swirl from the discs and therefore tend to reject the
hypothesis that the yellow discs were "connected" to the blue swirl.
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