A very good question. For the purposes of this document, being
left-handed means having a preference for using your left hand for
a variety of tasks, including reaching, throwing, pointing,
catching. It also implies a preference for using your left foot
for tasks such as kicking, as well as the preferred foot with
which to begin walking, running and bicycling. However, there are
no hard and fast rules for determining which hand or foot the
Lefthander prefers to use for a particular task. Most will prefer to
use the left hand or foot for delicate work.

One may also have a dominant left eye, preferring to use the left
eye for telescopes, camera sights, and microscopes.

In general, being left-handed means having a dominant right side
of the brain.

M.K. Holder <mholder@indiana.edu> clarifies that this dominance
does not apply in the area of brain hemisphere specialization for
language abilities: According to a neurological study published by
Branch, Miller & Rasmussen in 1964 (Journal of Neurosurgery
21:399-405) indicates that perhaps half of all left-handers
have the same left-hemisphere specialization for language
abilities as do right-handers. See:
http://www.indiana.edu/~primate/refs1.html for more information.

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Q02. What does being ambidextrous mean?
To be ambidextrous means to be equally dextrous with either hand.
That is, the ability to use both hands with equal skill and coor-
dination.

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Q03. What percentage of the population is left handed?

There have been many different numbers put forth, with the most
common numbers we have seen being in the area of 13 percent. However,
we have seen numbers as high as 30 percent, when you allow a
very loose definition of left-handedness.

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Q04. Is lefthandedness inherited?

While lefthanders undoubtably runs in some families, scientists
are unsure that the issue is completely resolved. Part of the
problem has to do whether a person's hand preference is the result
of genetic determination or some other reason ie forced to switch
because of convention, accident, what ever.

Mark Plonsky tells me that the book "Behavior Genetics" by J. L.
Fuller (1978) contains a 14 page section on laterality and
handedness. It concludes ". . . it is clear that the problem of
lateralization and its etiology is far from being solved. Since
it is probably one of fundamental importance, further work on it
would be very desirable." (p. 288).

There is a very interesting Web site on the issue of handedness
located at: http://www3.ncbi.nlm.nih.gov:80/htbin-post/Omim/dispmim?139900

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Q05. Are lefthanders naturally clumsy?

An emphatic NO to this. The problem most lefthanders have is that
the world is configured for right handed people. Lefties, in the
act of accommodating to this opposite world, may appear awkward
using tools that have right hand preference designed into them.
However, right-handers display even more awkwardness using left
handed tools than lefthanders do using right handed tools. This
is probably because righthanders are less used to adapting.

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Q06. Is there a quick test to determine eye dominance?

Try the following to determine eye dominance. With both eyes
open, line up the tip of your finger, at arm's length, with a
distant object. Close each eye separately. The eye that results
in the object and you finger remaining aligned is your dominant eye.

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Q07. Is there a quick test to determine handedness?

No, there is not. In fact, the only sure way to determine brain
dominance is to anesthetize one half of the brain and then see
what functions are still handled by the still functioning hemisphere.
There have been interesting results obtained, such as people able
to respond to visual cues but not verbal cues. I don't know about
you, dear reader, but I am not willing to submit to this test just
to definitively answer the question.

However, you can try this: Sitting comfortably, fold your hands
together and notice which thumb is on top. Lefties will have the
right thumb on top.

Readers should note that this test is not completely accurate. We
have heard about a significant number of lefties on alt.lefthanders
who fail this test. Readers should also note that hand preference
is usually not evident until children are age 4-6. Some children have
been known to exhibit a preference as early as age 2.

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Q08. What makes a cup right or left handed?

First, you must realize that (drinking) cups come in two varieties:
symmetric and not symmetric. Cups that are not symmetric may have
a lip to ease pouring the contents. If this kind of cup is right
handed, the lip will be on the side of the cup which is away from
the body, which allows for a easy neat motion. If this cup is
picked up with the left hand, the lip is toward the body, which
makes it awkward and messy to pour.
For symmetric cups, the problem is that when the decoration is only
on one side. When the right handed individual picks up a right
handed cup, he is able to see and enjoy the decoration. A leftie
using that cup presents the decoration to the world; he is unable
to see it.

Lefties would benefit with symmetric cups with designs on both sides;
cups with lips would have to be made in both right and left handed
varieties.

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Q09. What makes scissors right or left handed?

You can see the difference easily, by placing the scissors on
the table like this:

\ /
\/
/\
O O

For right-hand scissors, the part of the scissors lying `on top' at
the intersection of the two parts, will be the one from top-left
to bottom-right, whereas for left-hand scissors, the uppermost will
be the part from bottom-left to top-right. Turning the scissors around
or up-side down won't change this relationship.

Secondly the reason for this difference lies in the way the
scissors are opened and closed by your left or right hand. When you
close the scissors, the cutting edges close and the cutting edges
are pressed together because your fingers holding the scissors bend
and your thumb stretches. If the cutting edges are pushed away from
each other, the material being cut slides in between, and is definitely
not cut. This is what happens when you use a right-hand scissors
with your left hand.

Since your left hand is a mirrored version of your right hand,
your scissors should be `mirrored' as well. This is why the cutting
edges are made on the opposite side of each part, and the parts
are assembled just the opposite way, giving you perfect left-handed
scissors.

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Q10. What makes a bowling ball left or right-handed?

Left-handed bowling balls are different in two respects.
The first, and most obvious, is the placing of the finger holes
in relation to the thumb hole. What follows is the first (and
last) square bowling ball you'll ever see <G>:

0 0
0 0
+ +

0 0

The view is from the top and the spacing is highly exaggerated.
Mark Hideo Fujimoto <fuj@uclink.berkeley.edu> points out that
while this configuration is true for a vast majority of people,
one cannot say it is true in the general case.

The ring finger is held behind the middle finger, as it is then
the last thing to leave the ball - imparting spin. Using a right-
-handed ball, the middle finger, or the thumb, would be last.
Neither of these digits will impart any spin at all to the ball.
Spin is important to make the ball curve, or hook, into the pins
and the rotation of the ball stabilizes it as it drives through.

The second consideration, which I cannot draw (do I hear cheers?)
is the location of the center weight with relationship to the spot
where the holes are drilled. The ball is drilled so that the weight
is slightly ahead of the thumb hole and to one side - left, for
left-handers. This balancing weight provides extra momentum and
spin to the ball.

Mark Hideo Fujimoto <fuj@uclink.berkeley.edu> disagrees:
I have to disagree here, too. The "center weight", or more correctly,
the center of gravity of the weight block, is usually placed to the
*left* of the (+) in my diagram for a left-handed ball. This is known
as "positive weight", which combined with lift and spin imparted by the
bowler, gives the ball a more pronounced hook than a ball without this
type of weighting. Once again, this isn't the only way to drill
a bowling ball, but it is one that tends to be conducive to getting the
ball reaction that produces more strikes.There will be times when other
types of weighting will prove to be more beneficial than "positive"
weights.

Throwing the ball fairly normally for a beginner, one should
ideally see some clockwise rotation as the ball tends to drift
toward the center (a strike!). Throwing a right-handed ball with
your left hand places the weighting on the left side - meaning the
ball will go straight, or even back up (a reverse curve). This
kind of delivery makes it almost impossible to get the ball to the
center with force and momentum, unless you are a 300-pound gorilla.

Mark Hideo Fujimoto <fuj@uclink.berkeley.edu> clarifies:
you don't have to be a "300# gorilla" in order to overcome the effects
of various ball weightings. If a left-hander imparts a clockwise ro-
tation to the ball, regardless of whether it's a right-handed or left-
handed ball, the ball will hook from left to right. The weights may
alter the way the ball hooks (i.e., earlier, later, stronger, weaker.),
but not the direction in which it hooks. Many bowlers use "negative
weight" (placing the weight block's CG closer to where the ball rolls)
in order to reduce the amount of hook on lanes that promote hook (i.e.
"dry" lanes, lanes with little oil on them).

Most bowling establishments have a couple of left-handed balls
for use. These are usually in poor shape, but a lot better than
trying a right-handed ball, for the reasons stated above.

The good news is - a left-handed ball, drilled by a professional,
costs EXACTLY the same as the right-handed one. And, to spur your
confidence, don't forget that the first man to earn a million dollars
in bowling, Earl Anthony, is left-handed.

Thanks to: Bob Snyder <snyderr@buffnet.net>
Mark Hideo Fujimoto <fuj@uclink.berkeley.edu>

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Q11. What makes bowling shoes left or right-handed?

Bowling shoes are "handed" by the type of sole that is on the sliding
shoe. Since (most) left-handed bowlers slide with their right foot, the
right shoe is soled with some type of leather or buckskin to aid in
sliding. The left shoe will usually be rubber-soled with a leather or
a textured rubber toe piece. This toe piece is added for extra traction
when "pushing off" on the next-to-last step. Right-handed shoes are
basically mirror images of the left-handed shoes. Most bowling shoes
come in this configuration; however, some manufacturers produce their
low-end bowling shoes in ambidextrous versions -- both shoes have some
type of sliding sole, so they can be used by either left or
right-handers. House shoes are typically this way.

Thanks to: Mark Hideo Fujimoto <fuj@uclink.berkeley.edu>

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Q12. Where can I acquire left-handed guitars?

We have heard of the following places, but since we have not been
able to try them, the following list does not constitute a recom-
mendation. They are listed in no particular order:

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Q13. Do Lefties die younger than right-handers?

Stanley Coren, who is the author of "The Lefthander Syndrome" found
statistical evidence of this, and didn't believe it for the longest
time. However, he remains unable to disprove it. He was able to
demonstrate a possible reason for this might be that a left hand
startle reflex would be much more dangerous when driving a car
on US or Canadian road since the car would end up pointing
against traffic while a right hand startle reflex would simply
cause the car to drive of the road.

As a double check, Coren did find a statistical difference in
left handed traffic fatalities in countries where they drive on
the left, such as Great Britain or Australia.

Q14. Are Lefties brain damaged?
Q15. Do Lefties make better athletes?
Q16. Do Lefties make inferior athletes?
Q17. In baseball, what makes left-handed hitters so successful?

This may not be a true statement, but here is a possible ex-
planation:

A left-handed hitter faces the home plate from a different side.
For a pitcher who is not yet used to pitching to lefties, His
standard arsenal of pitches do not have the same affect. A normal
outside fast-ball to a right-hander becomes an inside fast-ball
to a leftie and the same is true for an inside fast-ball. Also,
a curve ball curves out for a rightie would curve in for a lefty.

The resulting confusion is what makes left-handers better at
hitting.

Edward Brekelbaum (eb3z@andrew.cmu.edu) adds:
Also, batters in the right side of the plate (lefties), are about
one step closer to first base (a righty must step over the plate to be
where a lefty started). This may not seem like a huge advantage, but
how many times has a runner been out "By one step".

John Mianowski <jmianows@ix.netcom.com> points out that
LH hitters are generally more successful against RH
pitchers. As noted, a RH pitcher's breaking balls (i.e. curves,
sliders, cutters) will break in toward the hitter. It's
always easier to hit a ball that's breaking in on you than
breaking away. LH hitters are therefore perceived as being more
successful than RH hitters because the great majority of
pitchers are right-handed.

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Q14. In baseball, what makes left-handed pitchers so successful?

There are three factors here. First, left-handed pitchers
stand on the mound facing first base, making it much easier to
spot base-stealing attempts, and to throw out the runner. Secondly,
the throwing arm of a lefty pitcher is more hidden from view of a
righty batter, making it difficult for the batter to gauge the pitch
as it's being thrown. Finally, lefties naturally tend to throw the
ball towards the left side of the plate (from the batter's
perspective), placing the pitch inside for a righty batter (which is
more difficult to hit).

Ironically, the perceived success of LH pitchers is primarily
due to their inherent advantages over the LH hitters that the
other teams put in their lineups to hit off the RH pitchers!
Often, managers will bring in a pitcher to face just one
hitter (LH-on-LH or RH-on-RH matchup), because of which
hitters are coming up soon, or even to try to force the
opposing manager to pinch hit to get HIS favorable matchup (the
hitting team gets to make the last change), but taking a good
hitter out of the game to do it.

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Q15. In cricket, what makes left-armed Batsmen so successful?

Left-armed Batsmen enjoy the same advantages as left-handed
hitters do in baseball. See the answer regarding baseball
hitters above. Note that many left-armed batsmen prefer
to hit from the left side, for an unknown reason.

The rough patch formed by the right-arm pace bowlers is
further away from the off side of a right-hand batsman than a
left-hander; a (right-arm) bowler bowling over the wicket is
closer to the stumps than one bowling round the wicket, and will
therefore tend to run on to the pitch in the follow-through.

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