Sunday, 2 October 2011

Have We Two Brains? (5)

“Is There One ‘Left-Brain’ & Another ‘Right-Brain’?” (5)
No, None Escientific Evidence Confirms That

No Scientific Evidence, indeed, indicates a correlation between the degree of creativity and the activity of the Right hemisphere. A recent analysis of 65 studies on Brain Imaging and the processing of emotions concludes that such processing cannot be associated Exclusively with the Right Hemisphere. Similarly, No Scientific Evidence Validates the idea that analysis and logic depend on the left hemisphere, or that the left hemisphere is the special seat for arithmetic or reading. Dehaene (1997) found that the two hemispheres are active when identifying Arab numerals (e.g. 1 or 2 or 5).

Other studies show that, when the components of reading processes are analysed (e.g. decoding written words or recognising sounds for the higher level processes, such as reading a text), Sub-systems of the Two Hemispheres Are Activated.

Even a capacity associated essentially with the right hemisphere – encoding spatial relationships – proves to be within the Competence of the two hemispheres; but in a different way in each case. The left hemisphere is more skilful at encoding “categorical” spatial relationships (e.g. high/low or right/left), while the right hemisphere is more skilful at encoding metric spatial relationships (i.e. continuous distances).

Brain Imaging has shown that even in these two specific cases, areas of both hemispheres are activated and working together. A more surprising finding, perhaps, is that the dominant hemisphere for language is not necessarily connected to right- or left-handedness, as had been thought. A widespread idea is that right-handed people have their language on the left and vice versa, but 5% of right-handed people have the main areas related to language in the right hemisphere and nearly a third of left-handed people have them located in the left hemisphere.

Based on the latest studies, therefore, scientists think that the hemispheres of the brain do not work separately but together for all cognitive tasks, even if there are functional asymmetries. As a highly integrated system, it is rare that one part of the brain works individually. There are some tasks – such as recognising faces and producing speech – that are dominated by a given hemisphere, but most require that the two hemispheres work at the same time.

This invalidates the “left brain” and “right brain” concepts. Even if they may have brought some benefit through supporting more diversified educational methods, classifying students or cultures according to a dominant brain hemisphere is highly dubious scientifically, potentially dangerous socially, and strongly questionable ethically. It is thus an important myth to avoid.

"Understanding the Brain", The Birth of a Learning Science, 2007, page 117

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