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LONDON - Left-handed people once suffered prejudice - the word "sinister" from the Latin for left came to mean "evil" or "unlucky".
But a study has found that sinistrality - which affects up to 15 per cent of the population and is more common in men than women - is linked with quicker thinking when doing tasks such as playing computer games or sport.
Australian researchers have shown that connections in the left and right-hand side of the brains, or hemispheres, are faster in left-handed people.
The study published in the journal Neuropsychology says the faster transformation of information in the brain makes left-handers more efficient when dealing with multiple stimuli.
Dr Nick Cherbuin, of the Australian National University, measured transfer time between the two sides of the brain by measuring reaction times to white dots flashed to the left and right of a fixed cross. He then compared this with how good participants were at carrying out a task to spot matching letters in the left and right visual fields which would require them to use both sides of the brain at the same time. "Extreme" left-handers were 43 milliseconds quicker at spotting matching letters across the right and left visual fields than right-handed people.
"These findings confirm our prediction of increasing efficiency of hemispheric interactions with increasing left-handedness," said Dr Cherbuin. He said people tended to use both hemispheres for tasks which were fast or hard and which required interpretation.
Chartered psychologist Dr Steve Williams said left-handed people tended to be better at using both sides of the brain. "It's certainly interesting. It's always been said that left-handers are different from right-handers in that they are less consistent with their left-handedness."
He said the research seemed to be consistent with prior research showing that left-handers used both sides of the brain for language, meaning they were more bicerebral. They become faster at it because they are having to use both sides of the brain more.
This can have benefits for naturally left-handed sports players. In football, being able to kick with either foot is a huge asset, because each foot like each hand is under opposite-side control. Left-handers also tend to have better backhands in tennis.
Between eight and 15 per cent of the population are left-handed with identical twins more likely to be so than the rest of the population.
Theories behind the reasons for left-handedness include exposure to higher levels of testosterone before birth while some claim ultrasound scans may affect the brain of the unborn child, causing more left-handedness.
Left-handed people can feel they have been given a raw deal by society. The first reason for this is the nomenclature of handedness. In many European languages, "right" stands for authority and justice - German and Dutch recht and French droit. On the other hand, the English word "sinister" originally meant "left" but came to mean evil or unlucky. Secondly, left-handed people are placed at a constant disadvantage because nearly all tools and devices are designed to be used with the right hand - an example being scissors, which are arranged so the line being cut can be seen by a right-handed user but is invisible to a left-handed user.
Indeed such was the stigmatisation of left-handers that until the latter part of last century, some Catholic primary schools in the United States punished children writing with their left hand. Baseball players and left handers Lou Gehrig and Babe Ruth wrote with their right after enduring such suppression as children.
It has also been claimed left-handers are more intelligent and creative than right-handers. In his book, Right-Hand, Left-Hand, Chris McManus, of University College London, says the proportion of left-handers is rising and they are higher achievers.
He says left-handers' brains are structured differently in a way that widens their range of abilities and the genes that determine left-handedness also govern development of the brain's language centres. He believes the rising proportion of left-handers is partly due to the rising age of motherhood as, statistically, older woman are more likely to give birth to left-handed children.
Left-hand test
Try this test for left-handedness is from the Left-Handers Association.
1. Imagine the centre of your back is itching. Which hand do you scratch it with?
2. Interlock your fingers. Which thumb is uppermost?
3. Imagine you are applauding. Start clapping your hands. Which hand is uppermost?
4. Wink at an imaginary friend straight in front of you. Which eye does the winking?
5. Put your hands behind your back, one holding the other. Which hand is doing the holding?
6. Someone in front of you is shouting but you cannot hear the words. Which ear do you cup to hear better?
7. Count to three on your fingers, using the forefinger of the other hand. Which forefinger do you use?
8 Tilt your head over on to one shoulder. Which shoulder does it touch?
9. Fixate a small distant object with your eyes and point directly at it with your forefinger. Now close one eye. Now change eyes. Which eye was open when the fingertip remained in line with the small object? (When the other eye, the non-dominant one, is open and the dominant eye is closed, the finger will appear to move to one side of the object.)
10. Fold your arms. Which forearm is uppermost?
If you have always considered yourself to be right or left-handed you will probably now have discovered that your body is less than total in its devotion to its favoured side. If you are right-handed the chances are that you were not able to be "right" 10 times.
* Left-Handers Association
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