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Tore
Thursday, October 7th, 2004, 08:11 AM
Are you a right-hander or a non right-hander?

The choices are somewhat different from the traditional "right-handed/left-handed" system of classification, although it ultimately proves too difficult to differentiate ambidexterity from left-handedness. Right handedness is defined as being right-hand dominant for all or virtually all activities by which the hands are necessary for (i.e. writing, throwing a projectile, etc). Left-handedness would include both distinct left-handers and those considered ambidexterous.

Tore
Thursday, October 7th, 2004, 08:31 PM
Interesting results as of now.

The right-hander:left-hander ratio in the population at large is approximately 9:1, although I would expect the ratio in this particular poll to be somewhat more balanced (because of the different criteria used).

The causes of left-handedness are surprisingly poorly understand, although from current research, it appears the trait is largely prenatally determined with a considerable genetic component (note: this cannot apply to 'handedness' as a whole, rather simply left-handedness, as it does indeed seem humans are, for the most part, genetically "right-handed" by default. The estimates are in consideration of what factors are involved when the differing phenotype, left-handedness, is expressed). One specific study(Neale 1986) estimates the heritability of left-handedness at around 20%, with 7% attributable to common environmental effects, and the remaining variance influenced by unique environmental (prenatal) events.

http://genepi.qimr.edu.au/staff/nick_pdf/CV346.pdf

Also of relevance...

"Lorin Elias, a psychology professor at the University of Saskatchewan, has a special interest in left-handedness, a characteristic that about ten percent of people exhibit and that often isn't clearly established until the age of six or seven. He agrees that the genetic component is significant, and quotes a meta-analysis (combining the results of many studies) done at St. Mary's Hospital Medical School in London, England in 1992. It found that two right-handed parents had a 9.5 percent chance of having a left-handed child; if one parent was left-handed, 19.5 percent of offspring would be left-handed; if both parents were lefties, 26.1 percent of their children would be, too."

http://www.todaysparent.com/preschool/education/article.jsp?content=251

"Approximately ten-percent of people are left-handed. If both parents are right-handed the chances for a lefty are two percent. If only one parent is right-handed, the chance of a lefty offspring increases to seventeen percent. If both parents are left-handed, it's about fifty-fifty. Also, twice a
s many males as females are left-handed."

http://www.wcax.com/Global/story.asp?S=1620122&nav=4QcVFCyV

I recall reading about an interesting theory in Coren's book ("The Causes of Consequences of Left-Handedness") which offered an interesting explanation of the phenomena. Essentially, Coren postulates the 90% of the population is "genetically right-handed," with the remaining 10% "genetically left-handed." Coren estimates that 10% of each group will undergo a prenatal "switch" in brain hemisphere dominance in response to a combination of events in utero. Therefore, the resultant frequencies will be 82% and 18% of right and left handers respectively, with 1% of the right-handed "pathological" right-handers, and half the left-handers exhibiting the same "pathology".

Tore
Friday, October 8th, 2004, 07:26 AM
Interesting differences between Left and Right Handers

Left handers are disproportionately male
Left handers have a slower on average rate of maturation than right handers (even after sex is controlled for)
Left handers have lower on average serum testosterone levels than right handers (at least, among males)
Left handers have superior on average visuo-spatial skills than right handers(likely relates to testosterone, rate of maturation, or a combination of both factors)
Left handers are overrepresented in fields such as architecture
Left handers are overrepresented in sports such as tennis and baseball (particularly in the position of pitcher; likely relates to more developed spatial visualization skills)
Left handers, as a group, have a higher IQ standard deviation than right handers (more geniuses and more learning disabled individuals)
Left handers score slightly lower, on average, than right handers on tests of fluid intelligence (matrix relations, reasoning skills, pattern recognition etc)
Left handers achieve slightly lower grades in school, on average, than right handers (overall difference in average was only 3%, although Coren notes that the disparity lnvolved higher marks for right handers in virtually every subject, and that it becomes more pronounced in later maturity and adulthood)
Left handers tend to score high on the personality traits of introversion and neuroticism, and tend to afflicted moreso with disorders such as Schizophrenia when compared to right handers
Left handers have a greater proclivity towards homosexuality and criminality
Left handers tend to be more field dependent than right handers
Autistic individuals are strongly inclined towards left-handedness or ambidexterity
Left handers may be more "creative" than right handers, with a certain predisposition towards musical and artistic endeavours (may relate to dominance or activity of the right hemisphere)

Most of the information is derived from the work of Stanley Coren, author of "The Causes and Consequences of Left handedness."

If a specific source is required, however, I shall provide it.

Siegmund
Friday, October 8th, 2004, 11:57 AM
Came across an interesting site (http://www.io.com/~cortese/left/southpaw.html) on lefthandedness.

The following list of famous left-handed people is just one item to be found there:


Norman Schwarzkopf
Martina Navratilova
Jimi Hendrix
Charlie Chaplin
Ted Williams
Shoeless Joe Jackson
Babe Ruth
Sandy Koufax
Steve Carlton
Jimmy Connors
John McEnroe
Gerald Ford
Earl Anthony
Leonardo da Vinci
Holbein
Raphael
Paul Klee
Picasso
Bob Dylan
Ringo Starr
Paul McCartney
Harpo Marx
Oprah Winfrey
Goldie Hawn
Jerry Seinfeld
Bruce Boxleitner
Harry Andersen
Whoopi Goldberg
Dennis Quaid
Matt Dillon
Andrew McCarthy
Howie Mandel
Diane Keaton
Phil Collins
Betty Grable
Howard Keel
June Allyson
Bruce Willis
Demi Moore
Ryan O'Neil
Richard Dreyfus
Tom Cruise
Natalie Cole
All of the Manhattan Transfer
George Michael
Ron Perlman
Mark Spitz
Sandy Koufax
Napoleon Bonaparte
Julius Caesar
Benjamin Franklin
Albert Einstein
Michaelangelo
Pablo Picasso
Jack the Ripper
Billy the Kid
Alexander the Great
George II
Queen Victoria
Prince Charles
James A. Garfield
Harry Truman
Nelson Rockefeller
Carl Phillip Emanuel Bach
W. C. Fields
Dick Van Dyke
Carol Brunett
Cloris Leachman
Danny Kaye
Peter Fonda
Paul Michael Glaser
Michael Landon
Robert Redford
Judy Garland
Marlyn Monroe
Kim Novak
Vida Blue
Ty Cobb
Whitey Ford
Reggie Jackson
Ron Guidry
The Boston Strangler
Stan Musial
Bob Charles
Sam Adams
Ronald Reagan
George Bush
Bill Clinton
Ross Perot
Brad Pitt

QuietWind
Saturday, October 9th, 2004, 03:12 AM
I am predominantly right handed, but have a tendency towards ambidexterity. My grandmother was a true ambidextrous individual. In myself, I write right handed, but can also write left. In Tennis I can use both hands and have a stronger backhand than forehand when using my right hand. When I was a gymnast, I was dominant left-handed, and always the only left dominant in my classes. I can't think of any other things off hand.

Tore
Tuesday, October 12th, 2004, 05:53 AM
I should also add too other interesting points Coren made note of.

Firstly, Blonds are more likely to be left-handed than those with hair of darker shades (within predominately White populations).

Secondly, left-handers have a peculiar tendency to die younger than their right-handed counterparts (the overall difference is nine years; twelve for males).

Dr. Solar Wolff
Tuesday, October 12th, 2004, 08:17 AM
I should also add too other interesting points Coren made note of.

Firstly, Blonds are more likely to be left-handed than those with hair of darker shades (within predominately White populations).

Secondly, left-handers have a peculiar tendency to die younger than their right-handed counterparts (the overall difference is nine years; twelve for males).

I am right-handed but do some things left-handed such as bat in baseball. My father was left handed but was changed over to being right handed as a child. In those days there was a prejudice towards left handed people. My wife is left handed and one of my three children is left handed. He is 26 and has blond hair and blue eyes.

A Chinaman once told me that "all Chinese are right handed". I pressed him on this and he came off of it a little saying all he had seen were right handed.

Tore
Tuesday, October 12th, 2004, 08:44 PM
In those days there was a prejudice towards left handed people.

There still is a prejudice in the sense that desks, notebooks, certain machinery and tools (drills, power saws, etc), as well as equipment in various sports (field hockey) are designed with the assumption that the individual using the device will be right-handed.


A Chinaman once told me that "all Chinese are right handed". I pressed him on this and he came off of it a little saying all he had seen were right handed.

There is a tremendous amount of cultural pressure within China that favours use of the right hand over the left. I recall reading that the incidence of left-handedness among Chinese diaspora is approximately ten times higher than the incidence among Hong Kong university students. I'll try to find the source.

Tore
Tuesday, October 12th, 2004, 09:39 PM
Males, Left-handers, and (mathematical) giftedness:
http://www.findarticles.com/p/articles/mi_m1175/is_v21/ai_4610401
(see: "The Causes and Consequences of Left-handedness" by Stanley Coren for further information)

Left-handers and Fluid intelligence:
www.masson.it/cortex/pdf/vol33/issue3/579-584.pdf

Left-handers, Schizophrenia, Autism, and Homosexuality:
http://www.narth.com/docs/lefthand.html
(see: "The Causes and Consequences of Left-handedness" by Stanley Coren for further information)

Left-handers and Field Dependence:
http://www.childrenofmillennium.org/eugenics/pages/psych4.htm

Left-handers and Serum testosterone levels:
http://cogprints.ecs.soton.ac.uk/archive/00001439/00/TANTANLAT.PDF.

Left-handers and IQ standard deviation:
(see: "The g Factor" by Arthur Jensen)

All other information is derived from "The Causes and Consequences of Left-handedness" by Stanley Coren.

Drömmarnas Stig
Saturday, October 16th, 2004, 07:07 PM
Hands -> left
Legs -> left
Brain -> right

Julius
Saturday, October 16th, 2004, 11:55 PM
Yes, I am a lefty.

I have never experienced any prejudice from people, rather the opposite. Many seem to think it's a bit exciting... An artist told me he wanted to be left-handed because he wanted to be more "unique".

At one time in school my teacher asked me to show that I could write equally well with my right and left hands. The truth is that I had lied about it, but all my classmates fell for my show since I only had to write my name on the black-board. They still believe I'm ambidexterous. :D

When I was a child I naturally ate with my fork in right hand and my knife in the left hand. My dad always commented on it at dinner so it became a sport to surprise him. Today I can control them with either hand. :P It's good since when eating in front of my computer I can eat with my left hand and control the mouse with the right hand. ;)

I had a left-handed teacher who had become right-handed by training. I tried it too but never had the patience to practice. I sometimes switch hand when taking notes at university. The notes are readable but it takes away my attention - I think more about how I write instead of what I write.

Nowadays I only use my left hand for writing. I really dislike it since my papers get all messed up with black lead and ink. Thank god for computer keyboards!