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Brain switching and the disappearing dots

By Murray Bourne, 28 Jun 2006

Bonneh's Illusion gives a fascinating insight into the way our brains work.

It turns out that our left and right brains switch for control of our consciousness. Where did this realisation this come from? The independent eyes of the sandlance fish move one at a time - indicating that the left brain is in control for a time and then the right brain is in control.


Prof Jack Pettigrew of Queensland University wondered whether human brains also switch between left and right hemispherical control. The Bonneh Illusion test indicates that the human brain certainly does switch.

When you concentrate on one of the fixed dots, the dots disappear among the swirling mass of blue dots. What is happening is that the right hemisphere is more likely to notice finer details whereas the left hemisphere is more aware of the big picture. As the hemispheres switch control, the dots are either important or not important and so appear or disappear.

» Try the Bonneh Illusion test.

But wait, there's more! The speed of brain switching reveals an interesting finding. Mathematicians show slow switching (less than 4 switches in 30 seconds) while dancers and musicians show fast switching (more than 6 switches). This makes sense in that mathematicians need to concentrate on one aspect of a problem for a long time whereas for dancers, small and large picture issues are constantly in play - and need to be 'refreshed' constantly.

My rate was 2 switches in 30 seconds, consistent with my mathematical leanings.

What they didn't talk about in the study was gender differences in brain switching. I would expect that women would have faster switching rates, due to their larger corpus callosum.

For a transcript of the ABC Catalyst item on this fascinating study, see Brain Switch.

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