INTENSITY²
Start here => What's your crime? Basic Discussion => Topic started by: skyblue1 on January 26, 2012, 07:56:13 AM
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Left-handers have been the subject of curiosity, stigma and even fear over the centuries. Researchers now, however, are recognizing the scientific importance of understanding why people use one hand or the other to write, eat or toss a ball.
Handedness, as the dominance of one hand over the other is called, provides a window into the way our brains are wired, experts say. And it may help shed light on disorders related to brain development, like dyslexia, schizophrenia and attention deficit hyperactivity disorder, or ADHD, which are more common in left-handed people.
Other recent research suggests that mixed-handedness—using different hands for daily tasks and not having a dominant one—may be even more strongly linked than left-handedness to ADHD and possibly other conditions.
About 10% of people are left-handed, according to expert estimates. Another 1% of the population is mixed-handed. What causes people not to favor their right hand is only partly due to genetics—even identical twins, who have 100% of the same genes, don't always share handedness.
More important, researchers say, are environmental factors—especially stress—in the womb. Babies born to older mothers or at a lower birth weight are more likely to be lefties, for example. And mothers who were exposed to unusually high levels of stress during pregnancy are more likely to give birth to a left-handed child. A review of research, published in 2009 in the journal Neuropsychologia, estimated that about 25% of the variability in handedness is due to genetics.
On average there is no significant difference in IQ between righties and lefties, studies show, belying popular perceptions. There is some evidence that lefties are better at divergent thinking, or starting from existing knowledge to develop new concepts, which is considered an element of creativity. And left-handed people have salaries that on average are about 10% lower than righties, according to recent research performed at Harvard University that analyzed large income data bases, although findings of some earlier studies were mixed.
Left-handedness appears to be associated with a greater risk for a number of psychiatric and developmental disorders. While lefties make up about 10% of the overall population, about 20% of people with schizophrenia are lefties, for example. Links between left-handedness and dyslexia, ADHD and some mood disorders have also been reported in research studies.
The reasons for this aren't clear. Scientists speculate it could be related to a concept known as brain lateralization. The brain has two halves. Each performs primarily separate, specialized functions, such as language processing, which mainly takes place in the left hemisphere. There is lots of communication between the hemispheres.
Typically in right-handers, the brain's left side is dominant. But this tendency doesn't hold up with lefties, as scientists previously believed. Some 70% of lefties rely on the left hemisphere for their language centers, a key brain function, says Metten Somers, a psychiatrist and researcher who studies brain lateralization at Utrecht University Medical Center in the Netherlands. This doesn't appear to present problems, scientists say.
The other 30% of lefties appear to exhibit either a right-dominant or distributed pattern, Dr. Somers says. They may be more prone to impaired learning or functioning, and at greater risk for brain disorders, he says.
Hemisphere dominance is typical and more efficient. Symmetry, in which neither side is dominant, is believed linked to disorders, researchers say. People with schizophrenia, for instance, exhibit more symmetrical activation of their brain hemispheres than those without the disorder, studies show.
In a 2008 study, Alina Rodriguez, a psychology professor at Mid Sweden University in Östersund who studies handedness, brain development and ADHD, found that left- or mixed-handedness in children was linked to a greater risk of difficulty with language as well as ADHD symptoms. In another study published last year in Pediatrics, involving nearly 8,000 Finnish children, Dr. Rodriguez found that mixed-handedness rather than left-handedness was linked to ADHD symptoms.
And knowing that a child was mixed-handed and had ADHD symptoms at age 8 helped predict much more accurately than just knowing they had symptoms at that age whether the child would continue to have symptoms at age 16. (What happens when people are forced to switch from writing with their dominant hand to the other isn't well known, experts say.)
One reason that not more is known about lefties is that many studies of how the brain works prohibit left-handers from participating because their brain wiring is known to be different, says Robin Nusslock, a psychology professor at Northwestern University in Evanston, Ill., who uses neuroimaging to study mood disorders.
Lefties have an advantage in sports such as tennis, fencing and baseball, when up against a righthanded competitor, but not in noninteractive sports such as gymnastics.
.A potential pathway between prenatal stress and brain wiring could be cortisol, the body's main stress hormone, which can interfere with brain development, says Carsten Obel, a professor at the public-health department at Aarhus University in Denmark who has conducted research on the prenatal environment and risk of disease. Cortisol is able to pass over the placenta barrier to influence the baby.
Several studies show that stressful life events, such as the death of a loved one or job loss, during pregnancy increase the risk of having non-right-handed children. In one study of 834 Danish mothers and their 3-year-old children, Dr. Obel and his colleagues found that mothers who reported multiple stressful events during their third trimester of pregnancy and experienced distress were more than three times as likely to have a mixed-handed child, 17% compared with 5%, according to the 2003 paper published in Developmental Medicine & Child Neurology.
Another large study followed 1,700 Swedish mothers and children until the kids were 5 years old. It found that mothers with depressive symptoms or who underwent stressful life events while pregnant were more likely to have left- or mixed-handed children. The work was published by Dr. Rodriguez and her colleagues in 2008 in the Journal of Child Psychology and Psychiatry.
Experts suggest that left- and mixed-handedness could be used as a risk factor for possible psychiatric or developmental conditions, along with behavioral difficulties, such as having a hard time in school. The presence of such risk factors could prompt early evaluation for those conditions, they say.
—Christina Tsuei contributed to this article.
http://online.wsj.com/article/SB10001424...52538.html (http://online.wsj.com/article/SB10001424...52538.html)
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You do post some interesting articles. Are you left-handed skyblue?
I am and I have ADHD. My twin sister is right-handed and she doesn't have ADHD.
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You do post some interesting articles. Are you left-handed skyblue?
I am and I have ADHD. My twin sister is right-handed and she doesn't have ADHD.
I am right-handed, but am very handy with both because of my work :)
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I'm left footed.
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I'm right-handed for most tasks but left-eyed. If I use a microscope or something with only one eyepiece, I use my left eye instead of my right one.
How do you determine right-footedness or left- footedness?
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^ Try kicking a ball. You'll notice straight away.
I'm right footed and right handed too. Bizarrely both my parents were (um, my mother still is ofc.) left-handed and their 3 kiddos all are right-handed. You'd say.. well, maybe..
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I'm right handed and right footed
Strongly in both cases
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^ Try kicking a ball. You'll notice straight away.
I'm right footed and right handed too. Bizarrely both my parents were (um, my mother still is ofc.) left-handed and their 3 kiddos all are right-handed. You'd say.. well, maybe..
I guess I'm ambi-footed, in that case. I took karate and I can kick well with either foot.
My parents were both right-handed, but one of my brothers was left-handed.
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Would you be able to kick a BALLL just as well though?
Taking a free kick with my left foot is incredibly difficult, and would never go where I aimed
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Would you be able to kick a BALLL just as well though?
Taking a free kick with my left foot is incredibly difficult, and would never go where I aimed
I think that I can kick a ball, a spot on a sandbag, or whatever with either foot fairly accurately. My legs are very strong, much stronger than my arms.
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I don't mean kick it as in making sure you foot comes into contact with the ball.I mean could you kick a ball at a target just as easily with either foot?
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^ Try kicking a ball. You'll notice straight away.
I'm right footed and right handed too. Bizarrely both my parents were (um, my mother still is ofc.) left-handed and their 3 kiddos all are right-handed. You'd say.. well, maybe..
Well, balls I do kick with my right foot. But all those jumping things at PE where you had to have a sideway approach, I was always standing with the lefthanded kids.
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For my youngest brother, very ambidextrous as a kid, apart from writing, that he did left-handed, they did seriously ponder on forcing him to learn to write right-handed, hoping it would help with his severe dyslexia.
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Posts in between but..
^ Try kicking a ball. You'll notice straight away.
I'm right footed and right handed too. Bizarrely both my parents were (um, my mother still is ofc.) left-handed and their 3 kiddos all are right-handed. You'd say.. well, maybe..
I guess I'm ambi-footed, in that case. I took karate and I can kick well with either foot.
Yeah, had a few lessons of karate too but try the ball thing one day (maybe in Spring.. um, well, suit self of course) but but but.. I'll bet you can't hit some tree (stem) from a spot 14/15/16 feet away with one 'that' easily and finding out that it would be quite a bit easier with the other.
Well, it doesn't matter much.
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Posts in between but..
^ Try kicking a ball. You'll notice straight away.
I'm right footed and right handed too. Bizarrely both my parents were (um, my mother still is ofc.) left-handed and their 3 kiddos all are right-handed. You'd say.. well, maybe..
I guess I'm ambi-footed, in that case. I took karate and I can kick well with either foot.
Yeah, had a few lessons of karate too but try the ball thing one day (maybe in Spring.. um, well, suit self of course) but but but.. I'll bet you can't hit some tree (stem) from a spot 14/15/16 feet away with one 'that' easily and finding out that it would be quite a bit easier with the other.
Well, it doesn't matter much.
I'll have to try that, but I doubt I would be able to kick a ball and have it hit a tree or its branch with either foot.
:laugh:
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^ Um, make sure there's no fragile windows nearby then. :laugh:
Oh, I totally suck kicking a ball with my left. It looks pathetic/gayish when I try. :celebrate:
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Even though I am left-handed, I do some things right-handed. Like ironing, knitting (though I am terrible at it) and batting at cricket or baseball. I am also left-footed (prefer to kick the football with my left foot).
I am definitely right-eyed though but that is because the vision in my left eye is bad.
My dad is left-handed and so was my maternal grandmother (though she was made to write with her right hand and so became equally good with either hand).
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I am right handed and batshit insane.
my sister is left handed and I think she might be a sociopath.
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That is really interesting Skyblue. :clap:
I am a leftie, but both my parents and all siblings are right handed.
I don't know if i posted this already, but the urchin, who has turned over a new leaf now at school is still struggling with writing and holding a pen. It appears he can't decide if he is left or right?
The teacher asked me what foot he kicks a ball with. This caused me some angst as i suddenly realised that no one has ever kicked a ball round with him. This is really really bordering on neglect in England. Little boys need to play footy.
So, i have been taking him to the park, and doing said activity. Rather badly.
It turns out, he has the same problem with his feet. I don't know what to do? Should i just try and focus on one or the other? I always thought it was wrong to push someone either way, but it is holding him back.
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Don't worry Bodi.
Time will tell, or not. And then there is still time to take action.
My oldest was doing just as much left as right handed and footed, till she was about five or six.
I had just bought her a pair of lefthanded scissors, because she liked the colours of them better than the righthanded ones, when all of a sudden, a preference for the righthand was there.
My youngest, she is born with a very strong right hand preference. Seems to be really weird, to see a preference that early and strong. It was so strong, that I got told to watch out for her growing faster at the right side of her body.
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I'm right handed and right footed
Strongly in both cases
Me too. I suppose I could train my left side but I can't be arsed. :tard:
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I once knew an old lady from England that said she was not allowed to be left handed in school. She was from Birmingham and if she is still alive she has got to be 90 years old. She said she would get smacked with a ruler if she wrote with her left so she learned to write with her right hand.
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body if i lived near u i would hapily teach the urchin some football lol. my little bros arent really into it. i cant imagine being left footed. even trying to picture in my head aiming a ball left footed is dificult. i also cant kick up off the floor v well with my left. altho i can do keepy uppies with both
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I once knew an old lady from England that said she was not allowed to be left handed in school. She was from Birmingham and if she is still alive she has got to be 90 years old. She said she would get smacked with a ruler if she wrote with her left so she learned to write with her right hand.
I believe the nuns harassed my sister about it and that was only in the 60's
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I once knew an old lady from England that said she was not allowed to be left handed in school. She was from Birmingham and if she is still alive she has got to be 90 years old. She said she would get smacked with a ruler if she wrote with her left so she learned to write with her right hand.
My father writes with his right hand but holds certain things, like brooms and shovels,
the way a left-handed person would. He suspects he started out left-handed and may
have been taught to switch to his right hand in school. (He's 85.) :chin:
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body if i lived near u i would hapily teach the urchin some football lol. my little bros arent really into it. i cant imagine being left footed. even trying to picture in my head aiming a ball left footed is dificult. i also cant kick up off the floor v well with my left. altho i can do keepy uppies with both
Thanks Adam. He could do with a more competent teacher than me, lol. I keep looking in the park, and the moment i see some nice older lads kicking a ball around i am going to try and bribe them.
He does like it. He sometimes just picks it up and turns it into a game of 'catch'
@Hyke. Thanks, that is reassuring to know about your kid, i don't know of anyone else that it has happened to.
@Parts and Eris. Yikes evil nuns. I'm in Birmingham, England too. I never got whacked though. I was a seventies baby, and i believe my parents made some attempt to get me to use the other hand. They even sought advice, but were told to leave me be. Maybe all the rulers were broken.
@cbc you are a right wing weeble :hahaha:
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@Parts and Eris. Yikes evil nuns. I'm in Birmingham, England too. I never got whacked though. I was a seventies baby, and i believe my parents made some attempt to get me to use the other hand. They even sought advice, but were told to leave me be. Maybe all the rulers were broken.
My youngest brother is a seventies baby too, but, they have really pondered on changing his writing hand, by the time he was past 10 I think, because of his severe dyslexia, and, because he was ambidextrous in all the other things.
They would not have used the ruler though. That may have been why they aborted the plan... Don't know. Will ask my Mum about that.
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I am the youngest in the family and a seventies kid also. By the time I was around my parents had sworn off catholic school after many many problems with my siblings . I would not have done well there even right handed between my sensory&motor issues along with dyslexia they would have said I was retarded like they did with my oldest brother
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My father writes with his right hand but holds certain things, like brooms and shovels,
the way a left-handed person would. He suspects he started out left-handed and may
have been taught to switch to his right hand in school. (He's 85.) :chin:
I am the opposite, left-handed but use a shovel and broom right-handed.
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My father writes with his right hand but holds certain things, like brooms and shovels,
the way a left-handed person would. He suspects he started out left-handed and may
have been taught to switch to his right hand in school. (He's 85.) :chin:
I am the opposite, left-handed but use a shovel and broom right-handed.
Interesting, do you know why? Are you ambidextrous in other ways? :nerd!:
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@cbc you are a right wing weeble :hahaha:
*commences long-winded political rant* :soapbox:
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My father writes with his right hand but holds certain things, like brooms and shovels,
the way a left-handed person would. He suspects he started out left-handed and may
have been taught to switch to his right hand in school. (He's 85.) :chin:
I am the opposite, left-handed but use a shovel and broom right-handed.
Interesting, do you know why? Are you ambidextrous in other ways? :nerd!:
Other ambidextrous examples I wrote above. I have no idea why, but they are all things that involve two hands. Maybe being shown that way had something to do with it? Not sure.
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My father writes with his right hand but holds certain things, like brooms and shovels,
the way a left-handed person would. He suspects he started out left-handed and may
have been taught to switch to his right hand in school. (He's 85.) :chin:
I am the opposite, left-handed but use a shovel and broom right-handed.
Interesting, do you know why? Are you ambidextrous in other ways? :nerd!:
Other ambidextrous examples I wrote above. I have no idea why, but they are all things that involve two hands. Maybe being shown that way had something to do with it? Not sure.
Ooops, I forgot to read all the new posts. Too busy replying! :blah: :blah: :blah:
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I write with my left hand and masturbate with my right. :orly: