Talk:Handedness

Staircase identified

The castle with the anti-clockwise spiral staircase mentioned in the article is Smailholm Tower near Kelso in the Borders of Scotland.—Preceding unsigned comment added by Adambisset (talk • contribs) 23:02, 15 December 2004

Shared material with left-handed

Moved to Talk:Laterality#From Talk:Handedness.23Shared material with left-handed. Please go there to continue merger discussion.

The removed material spans 10:25, 25 Jan 2005 to 03:12, 11 February 2006, and was moved from here at 10:27, 11 March 2006.

Resource intensive human brains.

The human brain is so expensive in turns of resources and energy consumption, that there has to be division of labor between the two sides of the brain. Only some functions can be duplicated. — Preceding unsigned comment added by Tabletop (talk • contribs) 02:22, 23 May 2005 (UTC)[reply]

The material above was removed without explanation (when adding other material) by 24.155.240.246 (talk · contribs · WHOIS) at 07:41, 9 November 2005, and is now restored at 06:18, 1 May 2009 (UTC). --Jerzy•t[reply]

Handedness of staircases in castle.

Assume

The defenders are on the top floor going down.
The attackers are on the bottom floor going ~~down~~up .

The spiral in the staircase should go the way that allows the defender's sword to swing into the centre pillar, for majority right-handers, a swing from right to left. This allows the defender to hit the attacker around the corner, almost. Let us call this a right hand spiral.

The same spiral in the staircase forces a right handed attacker's sword going uphill to swing from right to left away from the centre pillar, and into the outer wall, where it is reduced in attacking power.

This assumes that defenders and attackers are mostly righthanded. If possible, the attackers should use their left handers going upwards, if they have any, to lead the way.

If the defending force consists of lefthanders and they design the spiral of their castle staircases to go the other way, counter-intuitively and counter-productively, they make things easier for a right handed attacking force. A lefthanded spiral in a castle keep staircase suits a right handed attacking forces just fine.

Since attacking forces tend to outnumber defending forces, a left-handed defending force is still better off having right handed spirals in their Castle Keep staircase.
This wide spacing does not coincide with the end of Tabletop's contribution

Attention Noe
-- Tabletop 04:09, 24 May 2005 & 10:34, 26 May 2008 (UTC)
I am not disputing the story about the Kerr family with lots of lefthanders, building their castles with lefthanded staircases, but I do think that their effort is futile.
--— Preceding unsigned comment added by Tabletop (talk • contribs) 04:14, 24 May 2005 (UTC)[reply]

The cryptic reference to the Dab Noe would not have been cleared up even if TT had used "User:Noe", since Noe has piped their sig elsewhere on this talk page with "Niels Ø". Yikes!
--Jerzy•t 01:02, 1 May 2009 (UTC)[reply]

It appears that this is OR, and a guide to whether we should bother looking for refs to support it, not to what we can put in the accompanying article.
In any case, the outer front corners of the steps (to choose a clear point on each one) of a so-called "spiral" staircase trace approximately a helix. Since it is clear to most readers which handedness of bolt is intended when "right-handed thread" is specified, it's seriously confusing to describe (as i think TT has) a counter-clockwise-descending staircase as right-handed (doing so, i assume, simply bcz it is more convenient for right-handed defenders to fight facing down toward the attackers). The convention says it is a left-hand staircase that descends counter-clockwise and ascends clockwise, requiring the climber to keep turning right, and, other things being equal, presumably enhancing the defenders' chances, compared to a left-hand one, where only right-handers are involved.
If we grant your arguments, that changes the statement of your conclusions to

[What] allows the defender to hit the attacker around the corner, almost[, is called] a left hand spiral.

and

A left-handed defending force is still better off having left-hand spirals in their castle keep staircase.

--Jerzy•t 01:02, 1 May 2009 (UTC)[reply]

Of course, your reasoning leaves out many factors, perhaps foremost that there are so many factors favoring the defender (striking down from above rather than up advantages the force of the defenders' blows, controlling the space surrounding the staircase may asymmetrically provide protected positions for stabbing at attackers thru loopholes, in the absence of a prolonged siege the defender has short supply lines, etc.) that the main defense is to guarantee that taking the castle by main force will entail unacceptable losses by the attackers.
Finally, if you're rich in lefties, go ahead and build to create conditions that don't hinder them, and train them for those conditions. Your right-handed enemies won't be able realize their full theoretical potential for fighting better on your spiral staircase than on the usual right-handed-defender-favorable ones, because they've got to put their training time into getting experience at the more often relevant (and more difficult) task of fighting up a typical one. Your lefties get the same advantage of striking freely down that your righty attackers have to cope with on their righty neighbors' home ground, but the invaders' reflexes will be full of emphasis on defensive measures based the their usual difficulty of striking up on that the awkward side.
Odds are in any case that you'll never have to fight them, and certainty that you'd outlast them is not an achievable deterrent. Increasing the likelihood that their cost of outlasting you will be unacceptable to them might do more to deter them, than would reducing your own losses!
--Jerzy•t 01:02, 1 May 2009 (UTC)[reply]

The key difference between castles and say tennis courts, is that tennis courses are the same handedness either way, whereas a spiral staircase is one-hand going up and the opposite hand going down. This gives a rare left handed tennis player a consistant advantage, whereas with castle keep spiral staircases it depends ....— Preceding unsigned comment added by Tabletop (talk • contribs) 04:19, 24 May 2005 (UTC)[reply]

~~Tabletop 04:09, 24 May 2005 (UTC)~~[reply]

The immediately preceding struck-thru sig is a false sig, indeed placed by the contributor of the material above it, but misrepresenting the timing, and confusing the audits that rule out bad-faith forgeries. A copy of the sig has been placed back where it was before intervening, unsigned contribs were made by that contributor.

I have changed the article back (more or less), to mention your reservations about the usefulness of Kerr's staircases. --Niels Ø 19:05, May 28, 2005 (UTC)
this has nothing to do with sidedness!!!!!! grrrrr! —Preceding unsigned comment added by 137.195.176.12 (talk) 17:29, 25 February 2008
The IP placed this at the top of the section, so there's no telling what part of the content they had in mind.

What makes you right- or left-handed?

~~What makes you right- or left-handed?~~ It has been known since Darwin's day that left-handedness in humans runs in families, but it is not a simple system.

It appears that one gene (labelled 'D') causes people to have the textbook 'normal' asymmetries of the brain - leading to features such as being right-handed and probably also having the language centre in the left half of the brain and having hair that whorls clockwise on the head.

An alternative version of the gene (labelled 'C') is thought to fail to determine which side of the brain each specialised area will develop in, and so each such area has a 50 per cent chance of developing in either the left or right side.

This system means that people who have two copies of the 'D' gene will be right-handed (as well as having hair that whorls clockwise and a 'normal' brain configuration).

Taking sides People who carry two copies of the 'C' gene will have a 50 per cent chance of being left-handed - and are also thought to have a 50 per cent chance of every other asymmetry of the brain being in the opposite hemisphere from 'normal'. This explains why identical twins (which have the same genes) sometimes have different hand preferences.

People who have one 'C' and one 'D' gene have a 25 per cent chance of being left-handed and probably also a 25 per cent chance of each specialised region of the brain being in the opposite half from 'normal'.

So, if you are left-handed then you must have at least one 'C' gene. But, some right-handers will also have the 'C' gene - another external clue seems to be hair whorling anti-clockwise on the head, which is now also thought to indicate the presence of the 'C' gene.

If it is true that other areas of the brain are also affected by the 'C' gene, it might explain why left-handed people are over-represented among people with speech difficulties, schizophrenia and dyslexia - and some people with a 'C' gene may have a brain make-up that makes them particularly talented compared with 'normal' 'DD' people.

— Preceding unsigned comment added by 85.96.87.27 (talk) 21:03, 30 August 2005 (UTC)[reply]

The above material was removed by 85.96.87.27 (talk · contribs · WHOIS) 21:14, 4 September 2005}} without explanation, and is now restored at 06:18, 1 May 2009 (UTC). --Jerzy•t[reply]

Genetic evidence

A 2004 American Scientist article claims that handedness is genetic. [1] I don't know whether it is correct or not, but the inconsistency with the article should be resolved somehow. — Preceding unsigned comment added by Schlafly (talk • contribs) 18:59, 13 January 2006 (UTC)[reply]

No, that gives the current picture, which matches the data; it's partially genetic. Since identical twins can have different handedness it can't be totally genetic. But if you get one gene, you're righthanded, if you don't get that gene, then it's environmental. So, it's a mix. Gzuckier 19:31, 31 July 2007 (UTC)[reply]

Now that I look at the article (here on wp) again, i don't see that this is made clear. Hmm. Gzuckier 19:34, 31 July 2007 (UTC)[reply]

Right Hand, Left Hand (Chris McManus) gives a considerable amount of information on left-handedness being genetic, and this view is supported by a wealth of evidence. I believe the original author's view that it is not on this is almost certainly incorrect.http://www.righthandlefthand.com/ — Preceding unsigned comment added by 82.39.209.69 (talk) 23:07, 2 February 2006 (UTC)[reply]

My understanding is that lefthandedness is believed to be induced by increased levels of testosterone present in the womb. If that's true then lefthandedness per-se would not be genetic - but the tendancy for there to be excess of the hormone might well be. It is known that twin boys (not necessarily identical twins) have an increased tendancy towards lefthandedness due to the 'double dose' of testosterone the two brothers are getting. The probability of bearing twins would have to be genetically linked to the mother - not to the child - so the child might wind up being lefthanded without ever inheriting this hypothetical "high probability of male twins" gene from the mother. If the foetus produces more testosterone than usual during early development then that might be a direct genetic link to the child. So I don't think we can possibly be talking about anything as simple as "this little bit of DNA makes you left-handed" - but genetics clearly does have something to do with it. As with many such things, it's got to be a balance between genetic predisposition (both of the child and the mother) and environmental factors so we probably won't get a clear answer to this question. SteveBaker 18:58, 22 November 2006 (UTC)[reply]

Well, I'm left handed and in the last 100 years, so have all my female direct ancestors on my mothers side. Coincidence? PayneXKiller 21:27, 23 June 2007 (UTC)[reply]

that's well within what you'd expect to see via chance even if there were absolutely no genetic link. Assuming yourself and 3 other generations (since you don't specify), that leads to a basic probability of around one in ten thousand - how many people do you think have read this article? — Preceding unsigned comment added by 82.0.177.233 (talk • contribs) 14:38, 31 July 2007 (UTC)[reply]

Actually, it's me and 5 generations. And my ex girlfriend who is also left handed has a 4 generation backlog. Pretty big coincidence. PayneXKiller 23:35, 8 September 2007 (UTC)[reply]

Proposed merger

Moved to Talk:Laterality#Merger proposal. Please go there to continue merger discussion.

The removed material spans 02:55, 11 February 2006 to 10:16, 11 March 2006, and was moved from here at 2006-03-11 10:27:30

Writing Systems

In the context of writing, the article declares the motion is right to left. What about Arabic or Hebrew? Writing systems may be handed, but this article tacitly assumes that all writing systems are right-handed, which is "just plain wrong".— Preceding unsigned comment added by EmmetCaulfield (talk • contribs) 10:41, 26 October 2006 (UTC)[reply]

The earliest writing systems seem to have been right to left, perhaps because they were invented by lefthanders (17% of the population). But later on, the majority of writing systems tended to be left to right, perhaps becuase righthanders (83% of the population) were now writing a lot, and preferred L-R perhaps because they avoided smudging the ink. — Preceding unsigned comment added by Tabletop (talk • contribs) 10:46, 26 October 2006 (UTC)[reply]
- Cuneiform writing, which preceded paper or parchment, seems to me naturally to flow from right to left, because you're pushing with the right hand. Just my POV. Gzuckier 15:32, 26 October 2006 (UTC)[reply]

Information superceded by research

The information contained in this article is human-biased. It turns out that preference for a hand/claw/paw is prevalent throughout the animal kingdom and is therefore "genetic" though testosterone dosage in the womb could be a part of that, I suppose. And deviances from the animal kingdom might result from natural selection. Anyway here is a raw pointer to an article. There are many others.Student7 03:57 (2 edits), 1 December 2006 (UTC)
http://dsc.discovery.com/news/afp/20031027/walrus.html — Preceding unsigned comment added by Student7 (talk • contribs) 03:57, 1 December 2006 (UTC)[reply]

Great ref, but i invite you to try out a six-month moratorium on the term "animal kingdom". The ref not only doesn't use it, but explicitly limits its assertions to vertebrates. (I'm relieved we won't be subjected to a revival of "... when the worm turns.")
--Jerzy•t 20:19, 1 May 2009 (UTC)[reply]

Masturbation

Discovery: masturbation with the other hand is as difficult as writing. Please add a note somewhere about this.— Preceding unsigned comment added by 61.219.36.143 (talk) 01:04, 7 July 2007 (UTC)[reply]

I find masturbation with the left hand more natural, despite being right handed. Your assertion sounds like self-research... —Preceding unsigned comment added by 71.182.32.45 (talk) 18:36, 9 December 2008 (UTC)[reply]
- Thanks, ladies! I'll put those vivid images to work! --MadWank 06:18, 1 May 2009 (UTC)[reply]

Handedness in twins

Please also include some discussion on handedness in identical (monozygotic) twins. Typically, one twin will be left-handed and the other right-handed - not sure of percentages. Additionally, some left-handed people may have had a twin in utero who did not complete gestation. 72.179.166.33 21:04 & :05, 1 August 2007 (UTC)Megan

In animals

This section should be added. I know that I've heard about handedness in animals somewhere, and I'm sure it exists. Someone wanna do a little research? --208.115.202.219 01:08, 10 August 2007 (UTC)[reply]

I know horses have handedness (eh, hoofedness). That is, they execute turns/etc. better in one direction than in the other, perform asymmetrical gaits better on one side than another, and work in a circle better in one direction than another. I won't be contributing to the article, but I wanted to show moral support... 24.211.245.220 (talk) 21:24, 20 September 2008 (UTC)[reply]
- But the article clearly states "Handedness is an attribute of human beings...". Help! Jidanni (talk) 04:06, 28 December 2008 (UTC)[reply]
  - Animals do exhibit a preference for laterality, but it's not what could be called handedness, i.e. it doesn't have to do with hemispheric specialization for language and it's found to be more like 50/50, not 90/10. The exception is with non-human primates; they do exhibit something closer to human handedness because they have some limited capacity for language. Source was an article I Google-Scholar'ed quickly: Fagot and Vauclair, "Manual Laterality in Nonhuman Primates: A Distinction Between Handedness and Manual Specialization", Psychological Bulletin, 109, 1, 76-89. Phtalo (talk) 11:58, 17 May 2009 (UTC)[reply]

The origin of right-handedness: Was it the way mothers carried their children?

In a popular German book about language and its origin, I found a compelling theory about how right-handedness may have developed. It runs like this:

The heart is (for some reason) on the left side. Because children are soothed by the sound of the heartbeat, possibly because it is familiar to them from pregnancy, mothers instinctively carried their child so that is was closest to the mother's heart. Before prehistoric carrying slings were developed, this meant carrying it with the left hand. This, in turn, left the right hand with most of the tasks that required fine motor skills. And that, according to the theory, is how right-handedness came about.

The theory is taken from So kommt der Mensch zur Sprache (How mankind acquired language / how humans learn to speak) by Dieter Zimmer, a writer and frequent contributor to the weekly newspaper Die Zeit. I don't have the book at hand right now, so I don't know whether Zimmer provides any references, and I don't know the page number, but I will provide that within the next few weeks.

Personally, I find the theory quite convincing, so I think it should at least be mentioned.

Tracerbullet11 16:07, 4 September 2007 (UTC)[reply]

Nonsensical statement?

The statement "Lastly, since other people do not have a spoken language (at least of the type we have) there would be no stimulus for right-handed preference among them, and that is true" is incomprehensible to me. Who are "other people"? Other than whom? As far as I know, people do have spoken language. and what is this "at least of the type we have"? Who are "we"? I don't get this weird "we" versus "other people". Surely, anyone who is a person might be reading this document and therefore might be regarded as part of "we". I think someone should just delete this uncited line if nobody jumps up to defend it anytime soon. Xezlec (talk) 20:47, 23 December 2007 (UTC)[reply]

Oldest writing systems written Right to Left

Would it be true to say that the oldest writing systems, of which Semitic languages are some, were and still are written Right to Left? This would suit lefthanders who can see what they are doing and not smudge the ink. Can we infer from all this that writing may have been invented by the minority of lefthanders. Later on, when righthanders started to write too, they changed early writing systems such as Ancient Greek to go Left to Right to suit righthanded writers who were in the majority? Tabletop (talk) 10:41, 26 May 2008 (UTC)[reply]

I heard once that if you're writing on a stone wall with a chisel it's easier to start at the right. I can't quite picture how this works, though. —Tamfang (talk) 06:52, 14 July 2008 (UTC)[reply]

If nothing else, chiseling on stone does not present the problem of smearing ink. —Preceding unsigned comment added by 71.111.205.221 (talk) 21:44, 20 September 2008 (UTC)[reply]

Hebrew, Arabic, and Sanskrit are written by hand from right to left. I put a "globalize" tag on the section. --Una Smith (talk) 21:07, 29 September 2008 (UTC)[reply]

Sanskrit? In which script? —Tamfang (talk) 18:16, 1 October 2008 (UTC)[reply]

Ah! Okay, delete Sanskrit. I had no idea it was so complicated. An expert on Sanskrit taught me to write some words in Sanskrit. Each word did have had a connecting bar on the top, which judging by the examples on Sanskrit places the script I used in a small category. I hope that is useful information. --Una Smith (talk) 04:02, 3 October 2008 (UTC)[reply]

Scripts with a connecting bar (sutra = 'thread') include Dẽvanãgarĩ (used for Hindi and Sanskrit), Bengali, Gurmukhi (used for Panjãbi) – none of which is written RTL. —Tamfang (talk) 05:17, 12 December 2008 (UTC)[reply]

Dubious epilepsy poll

A single editor offered an indented quotation, then proceeded to comment on it without indentation:

Also, a Sept 18th 2007 informal poll at the Epilepsy Foundation came up with a dramatic skew in percentages of handedness among epileptics of 19% right-handed, 24% left-handed, and 57% mixed or ambidextrous.

I don't like this sentence. The main reason, aside from the fact that there's no citation, is that it's an informal poll, thus conducted without any scientific rigor, and thus can be interpreted many different ways. The results are essentially meaningless.

For example, consider this highly OR interpretation of the poll that I came up with. Most lefties I know are somewhat proud of their left-handedness, probably stemming from the basic human need to feel special or set oneself apart from the crowd. Therefore a lefty is more likely to, without hesitation, report left-handedness.

A righty, on the other hand, does not have this luxury, but yet still retains the same human need to feel special. Thus, when presented with a multiple-choice questionnaire (or especially a public "hand-raising" poll, which this could have possibly been), the righty is much more likely to see the one or two little things he can do with his left hand and say "hey, I'm mixed-handed!"

Therefore, it's very possible that a large percentage of the self-reported "mixed" and "ambidexterous" people are in fact righties convincing themselves that they're special.

Without the scientific formalities designed to minimize the effects of such psychological factors, the poll results are essentially meaningless.

Oh, and yes, there's no citation. Mbarbier (talk) 14:46, 9 July 2008 (UTC)[reply]

Nobody's come out to defend this, so I'm gonna be bold and delete this poll. Mbarbier (talk) 15:19 (2 edits), 3 August 2008 (UTC)

droit(e)

I changed the passage about French words (but there's still room for improvement). The word droite is a feminine adjective; la droite is elliptical for la main droite (the right hand). It is thus not only "related" to droit meaning 'straight', it is the same word. —Tamfang (talk) 10:02, 4 October 2008 (UTC)[reply]

Questionable Section

I feel like the following section not well supported, and would like to ask you guys how you feel about removing it.

Asymmetry of internal organs
While the external organs are highly symmetric, the internal organs such as heart and stomach are highly asymmetric. Perhaps the asymmetric brain piggybacks onto this.
Some ambidextrous individuals note that they prefer sleeping on their right side, putting less overall weight on the heart-side of the body. Perhaps this unconscious preference to elevate the left side of the chest cavity to reduce the amount of work that the heart must exert during sleep favors the right side by supplying extra blood (due to gravity), widening the diameter of vessels within the right side of the body to compensate for the increase in pressure, thus, over time increasing that side's muscle efficiency.

The quote above reads a lot like an essay to me. I feel like it's probably WP:OR, especially since no citations are included. – Novem Lingvae (talk) 08:53, 31 January 2009 (UTC)[reply]

Agreed, it's so very speculative without sources. I also don't see the content of this passage as being relevant at all. Phtalo (talk) 12:14, 17 May 2009 (UTC)[reply]

Lessen duplication?

I agree that Lateralization and Handedness should probably not be merged. But i came to this talk page bcz of a sense that there is excessive duplication among

Handedness

Right-handedness

Left-handedness, probably

Mixed-handedness and

Ambidexterity, and perhaps

Lateralization of brain function.

Excessive overlap is onerous for users reading more than one of the suite of articles, and may further be the vehicle for PoV-forking re social aspects handedness, or re pet theories on the emerging science. IMO these problems are impracticably clumsy to clean up, in the absence of a rough consensus on where the various overlapping subtopics should be thoroughly covered, leaving the other articles in the suite to make reference to the appropriate section elsewhere, probably with brief passages setting at least one of the two pages in the other's context. This talk page struck me as the right place to look for such a consensus; having plowed through it and found only the lks to the merge discussion, i expect that it does not yet exist (but would be grateful for a lk if it does). Am i wrong in thinking that such a consensus is both useful and feasible?
--Jerzy•t 05:10, 2 May 2009 (UTC)[reply]

At the risk of rushing that process, i'm redoing the lead sent of Right-handedness, which i find awkward anyway, and essentially discarding both clauses of the third sentence. Seeing no interest yet in the suite-wide organization issue, i'll justify this for the time being only at Talk:Right-handedness#Lead secn & relationship to other handedness-oriented articles .
--Jerzy•t 18:24, 5 May 2009 (UTC)[reply]

Clusterizing this talk page

There are now 18 sections on this talk page. While we can usually get along w/o much attention to organizing the talk, it's hard to get a grasp of what's been worked out already. I propose to subordinate most of the existing sections into sections for related topics, roughly as follows: (The numbers represent order in the talk page's current state.)

Consequences

1 #Staircase identified

4 #Handedness of staircases in castle.

10 #Masturbation

Talk & Article Organization

2 #Shared material with left-handed

7 #Proposed merger

19 #Lessen duplication?

20 #Clusterizing this talk page

Etiology: theories and potential evidence

3 #Resource intensive human brains.

5 #What makes you right- or left-handed?