Sunday, 22 November 2009

Improve Your Memory (2)

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Improve Your Memory (2)!"
Only A few People Have Eidetic Memory

What about those people who have a visual, almost photographic memory, who are very good at memorising a long list of numbers drawn at random or capable of simultaneously playing several games of chess blindfolded? Researchers have come to attribute these performances to specialised ways of thinking, rather than to a specific type of visual memory.

DeGroot (1965) took an interest in the great chess masters, getting them to co-operate in experiments where the layout of the chessboard was briefly shown and these excellent players had then to recreate the layout of the pieces. They succeeded at this challenge perfectly, except when the layout shown had no chance of happening during a real game of chess.

The conclusion DeGroot drew was that the ability of the great players to recreate the layout of the chessboard was thus not due to visual memory, but rather to the capacity to mentally organize the information of a game that they knew extremely well. On this view, the same stimulus is perceived and understood differently depending on the depth of knowledge of the situation.

This work notwithstanding, some people do seem to possess an exceptional visual memory, which can keep an image practically intact. This is “Eidetic Memory”. Some people can, for example, spell out an entire page written in an unknown language seen only very briefly, as if they had taken a picture of the page. The eidetic image is not formed in the brain like a picture, however – it is not a reproduction but a construction. It takes time to form it and those with this type of memory must look at the image for at least three to five seconds to be able to examine each point. Once this image is formed in the brain, the subjects are able to describe what they saw as if they were looking at what they describe.

By contrast, normal subjects without eidetic memory are more hesitant in their description. It is interesting (and possibly unsettling) to know that a larger proportion of children than adults seem to possess an eidetic memory; it seems as if learning, or age, weakens this capacity (Haber and Haber, 1988). These researchers also showed that 2-15% of primary school children have an eidetic memory.

Leask and his colleagues (1969) found that verbalisation while observing an image interfered with the eidetic capture of the image, thus suggesting a possible line of explanation for the loss of eidetic memory with age. Kosslyn (1980) also sought to explain this negative correlation between visual memorisation and age. According to his studies, the explanation resides in the fact that adults can encode information using words whereas children have not yet finished developing their verbal aptitudes.

There is still lack of scientific evidence to confirm or contradict these explanations. Brain imaging studies on this are needed.

"Understanding the Brain", The Birth of a Learning Science, 2007, pages 120 - 121

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