Left Handed - Right Handed

K C Cheng kccheng at postoffice.idirect.com
Mon Mar 30 10:29:17 EST 1998


John Gorst wrote:
> =

> I am currently doing course work for 'A-Level' Biology.
> =

> The course work is based on the 'learning curve' in humans. The experim=
ent will
> basically be that the subject has to draw around a quite complex shape =
using one
> hand then the other - then repeat them both viewing it in a mirror. The=
 subject
> will be timed when doing this. They will repeat each possible combinati=
on 6
> times.
> =

> I am expecting the following results:-
> There will be very little improvement in the times when the subjects ar=
e using
> their right hand viewing it normally.
> There will be a considerable improvement when they do it with their lef=
t hand,
> when viewing it normally.
> There will be a continual improvement when they do the test using a mir=
ror - the
> 'curve' will continue when they swop hands.
> =

> I have to find biological reasoning for these improvements.
> I am going to say:-
> =

> - there is little improvement in the right hand as the neurological pat=
hways
> controlling it are fully developed.
> =

> - there is an improvement in the left hand as the neurological links as=
 being
> developed. Although the left hand will not get as good as the right han=
d in such
> a short length of time as there has to be cell growth to do this (I had=
 the idea
> that the myelin sheath was not fully developed around the neurones cont=
rolling
> the left hand therefore the control of it is not as fast and not as acc=
urate due
> to slower propergation of signals and interference - is this correct???=
)
> =

> - there will be a continual improvement when doing the test in a mirror=
 as there
> is only ONE part of the brain which controls eye to hand co-ordination.=

> Therefore there will be a continuation in the 'curve' between the left =
and right
> hands when viewing through a mirror as the neurological pathways are be=
ing
> established benefit the use of both hands.
> =

> Could you give me your view on the above reasoning.
> What I need is some definite biology behind 'building neurological path=
ways' as
> this is a very vague statement. Also what part of the brain controls ey=
e to hand
> coordination? There part of the brain which 'flips' the image from the =
eye
> vertically - does a similar thing happen when you do a activity looking=
 at it
> through a mirror but on a horizontal plane?
> =

> Note:- when I say left and right hand.... for the purpose of this exper=
iment I
> am going to use major and minor hand but I forgot to use these expressi=
ons in
> this article.
> =

> Thanks for any help
> =

> (could you please post to the newsgroup and via e-mail as my ISP curren=
tly has a
> 12 hour backlog on their news and is possibly loosing quite a lot of ar=
ticles -
> but I will be keeping an eye of this NG)
> =

> --
> JG
> john at gorst.demon.co.uk
RE. the above:
Your expectation that the R hand  would improve little, but L hand
imprives a lot more is not necessarily  right.  It depends on  lots of
factors  such as whether your left hand(R. hemisphere of the brain)  is
still capable of  rapid learning, etc.,.  If not,  or if the experiment
is repeated only few times,  the right hand would do much better or
improve more  than  what the left could.  That is because the right hand
link with the brain is much better developed and therefore can learn a
new task much faster and better.   However, if given years, it is
possible for the left to improve, relative to its earlier performance, =

more than the right.  =

The hand-to-eye coordination acquired in this kind of experiments has to
be generally at the cerebral level, namely  between the visual cortex
and the  sensory and motor strip on either side of the central sulcus. =

Since the cortical fibers link to all other parts of the brain,  this
type of facilitated linkage through learning is only natural.
Whether a person can  "flip" an image as you say, depends on learning
and individual "intelligence."
http://webhome.idirect.com/~kccheng =

kccheng:=B9=BF=C2=F7=F7=F7=F7=F7=A5=BB=BC=A7



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