Word meaning left and right handed

Handedness is the most common and most understandable term. But I’m going for my pedant merit badge, so I’m going to draw upon and explain the other suggestions.

A history and evolution of meaning: Chiral

@DanBron suggests the technical term Chirality:

The word chirality is derived from the Greek, χειρ (kheir), «hand», a familiar chiral object.

An object or a system is chiral if it is distinguishable from its mirror image; that is, it cannot be superposed onto it.

There has been a great degree of speculation as to whether chirality is applicable to the specific chiral orientation or if it is merely the property of being non-superposable. To clear it up, consider the following definitions.

chiral
adjective, Chemistry
1. (of a molecule) not superimposable on its mirror image.

_{chirality. (n.d.). Collins English Dictionary — Complete & Unabridged 10th Edition. Retrieved April 28, 2015, from Dictionary.com website: http://dictionary.reference.com/browse/chirality}

Chiral is the adjectival property of whether an object possesses symmetry, dissymmetry; whether it is superimposable or it is achiral/amphichiral. These have the same definition: not chiral; lacking any chirality in the same way that asexual means non-gendered; neither male nor female. In chemistry, pairs of molecules with opposite chirality are called enantiomer’s, sometimes optical isomers; in mathematics enantiomorphs is more common.

chirality
noun
1. the configuration or handedness (left or right) of an asymmetric, optically active chemical compound. Also called dissymmetry

_{chirality. (n.d.). Collins English Dictionary — Complete & Unabridged 10th Edition. Retrieved April 28, 2015, from Dictionary.com website: http://dictionary.reference.com/browse/chirality}

Chiral is a quite new addition to the English language, having only been though up by Lord Kelvin in 1893. The definitions for the word in technical fields and common language are evolving, but the suffix -ity is winning out for the meaning of chirality.

Used to form a noun from an adjective; especially, to form the noun referring to the state, property, or quality of conforming to the adjective’s description.

Handedness vs. Chiral

Handedness is commonly used to distinguish between the distinct items of a chiral pair – indeed, almost every definition or explanation of chirality I’ve heard (or Google suggested just now) uses the mirror symmetry of human hands as a prime example. For instance in physics, for subatomic particles that have a spin, one will be referred to as having left-handed spin, the other as having right-handed spin. It’s also applied to describe helix structures (DNA/RNA and threaded screws), electromagnetic and other vector fields where the right-hand-rule is well known, knots and several other geometric and mathematical notions.

JasonC suggests that handedness is a behavioral preference and therefore chirality is not an applicable synonym. However, manual dexterity is as least much a matter of skill as preference. Becoming a switch hitter in baseball requires a great deal of work. Many highly trained and motivated professional athletes do not succeed at overcoming this behavioral preference even though it provides a noticeable advantage to their career. People tend to see their hand dominance (or preference) as a part of themselves, a defining characteristic. In that sense, handedness is as much a physical configuration as a behavioral one.

Chirality is technically correct when applied to people’s hands, but almost never used. (That’s part of why I like it; it’s the best kind of correct.) However, in American English, it’s not the right way to ask a person about themselves, mostly because it doesn’t communicate the question as several commenters have pointed out. Communication will fail at a rate inversely proportional to the renown of the words (and grammar) used; the words chiral and chirality are not well known by many people without specialized knowledge of science, technology, engineering or math, so don’t use chirality. It is not used and will not be understood in common language. If you’re pitching a design for a nightlight (or even a horror movie), you can’t just say «Are you scotophobic, nyctophobic, lygophobic or achluophobic? Then you’ll love this!»

I’m basing my suggestion against chirality and the rest of this answer on the assumption that anyone talking about their designs is seeking to communicate with a broad audience. In short, you question sounds like you’re trying to market your designs and marketing messages that are not understood often achieve the opposite of the desired effect. You will drive your clientele away if they don’t understand you with minimal effort. If you are specifically trying to be coy and pique their interest by challenging their assumptions, I still suggest you stay away from uncommon technical terms. Unless you are speaking directly and exclusively to an audience you have every reason to expect will know the term chirality, I suggest you don’t use it.

Furthermore, chirality might be assumed by people who know the greek root to referred to hand preference. Or a listener might assume you’re asking about their hand preference because our left and right hands are the most ubiquitous identifiers of our asymmetry. But technically speaking, chirality could refer to any aspect of human asymmetry, of which there are many: wrists, elbows, shoulders, legs, feet, kidneys, ears etc. etc. all cannot be superimposed on their mirrored pair in the body.

• I lost a foot to a tractor accident.
• My left nostril is slightly larger.
• Every body part I have two of.

Are all correct and applicable answers to the question «What is your chirality?»

But even replacing it with the strict synonym ‘handedness’ can be confusing.

Eliciting a left-or-right response

I think your first example is best filled by using two words (and to hell with the single-word-request tag). I think it’s far more common and understandable to ask:

What’s your dominant hand?

This makes it most clear that you’re interested in an either-or, left-or-right answer. As some commenters point out, handedness is a spectrum; some people may write with one hand and eat, brush their teeth, cut their food etc. with the other. Nonetheless, when asked directly about which hand is dominant, most people will correctly identify that it’s left or right, map it to whatever activities they consider most important, and answer ‘left’ or ‘right’.

_{I’m basing this on the asker’s mention of «state of being left- or right-handed» indicating the desire for an either-or, binary answer. If you want a nuanced answer on a spectrum, use the more open ended «handedness» option.}

Inclusive instead of Exclusive language

Similarly, I think it would be very weird to hear:

Our designs do not bias against gender. Our designs are a-gendered/gender neutral.

Our designs do not bias against handedness. (Or, for that matter…)

Our designs do not bias against chirality. Our designs are achiral/chiral neutral.

The distinction itself — gender or handedness — isn’t what you’d be biased towards or against. That phrasing implies your designs are for suitable for both gendered and asexual people (or handed and ambidextrous people). I think what you’re trying to convey is that your designs are suitable for all people, whether they left-handed, right-handed or ambidextrous. Therefore, I humbly suggest (or rather second Chris H.’s suggestion):

Our designs are ambidextrous.

The prefix ambi- is inclusive, meaning both, unlike a prefix of un- or a- which would mean neither. Saying a person is ambidextrous means they use both hands equally well. Saying an inanimate object or design is ambidextrous implies that people can use either hand to hold, use or operate it equally well. A steering wheel is ambidextrous — it would be hard to imagine one that wasn’t (because circles lack chirality). A gear shifter is typically right-handed in cars with a left-handed driver seat (and vice-versa in Britain, e.g.).

And if you’re talking about an animate object, ambidextrous is the only way to go!

Our robot designs are ambidextrous.

As you correctly point out, however, you can’t remove the prefix from ambidextrous and make any kind of sense. Dexterity by itself doesn’t describe handedness or chirality. If you ask someone about their dexterity, you’d get a wide variety of interpretations — my grandmother would start talking about knitting and I’d roll three six-sided dice.

Sliding back into the marketing angle, promoting your product or design as not biased is taking a defensive tone. It is building a subtle connection in the listeners mind between your product and bias. I suggest you try very hard to find a positive or neutral way to describe your designs.

A washbasin with the tap on the center is, then, handedness-blind or chirality-blind, if you will.

It’s also precisely ambidextrous.

ambidextrous
adjective
1.1 (Of an implement) designed to be used by left-handed and right-handed people with equal ease:

_{ambidextrous. (n.d.). In Oxford Dictionaries. Retrieved April 29, 2015, from http://oxforddictionaries.com/definition/english/ambidextrous}

Several types of research, studies, and arguments suggest different intellectual and creative levels in left-handed and right-handed people. While people used to believe that left-handed people are more intellectual, with due time this theory has been proverb wrong. Though the right and left hemispheres of the brain respond differently for both handedness, there is no study to prove one is intellectually superior to the other.

Key Takeaways

1. Left-handed individuals use their left hand for primary tasks, while right-handed individuals rely on their right hand.
2. Right-handed people comprise approximately 90% of the population, with left-handed individuals accounting for the remaining 10%.
3. Society and products often cater to right-handed individuals, making certain activities more challenging for left-handed people.

The difference between left-handed and right-handed people is that left-handed people use their left hand for doing most of the tasks like lifting, writing, eating, etc. Right-handed people have their right hand as the dominant hand and use it most of the time. For left-hand people, some daily activities might get difficult that are made in convenience with right-handed people like zipping, swiping cards, etc. 

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Left-handed people comprise only 10% of the total world’s population.  Left-handed people tend to show less brain lateralization which means that both sides of their brain show fewer differences. Since the population of left-handed people is very very little, during middle age they were accused of being witches. 

Right-handed people are dominant in terms of population as they comprise 90% of the total world’s population. Since right-handed are present in the majority, some certain activities or devices are designed according to them. For example, in a computer lab, the mouse is always present on the right-hand side. 

Comparison Table

Parameters of Comparison	Left Handed	Right Handed
Meaning	In left-handed people, their left hand is more dominant and they find it difficult to perform tasks with their right hand.	In right-handed people, their right hand is more dominant and they find it difficult to perform tasks with their left hand.
Population	About 10% population of the world are left-handed.	Right-handed people comprise 90% of our world’s population.
Health Risks	Left-handed people are more prone to diseases like dyslexia and ADHD.	Right-handed people are not prone to any disease due to their handedness.
Difficulties	Some everyday tasks like putting on a zipper, swiping credit cards, using computer mouses become difficult for left-handed people.	Right-handed people do not face any difficulty using or operating any devices.
Brain Lateralization	Left-handed people show less brain lateralization.	Right-handed people show more brain lateralization.
Ultrasound	Some experts say that ultrasound has effects on causing left-handedness.	Unborn right-handed babies are not affected by ultrasound.
Genetics	Left-handed parents are more likely to have left-handed children.	Right-handed parents don’t have much influence on the handedness of their children.

What is Left-Handed?

 The left-handed people have suffered a lot during the Middle Ages as they were punished thinking they were evil and practicing witchcraft. Even during the 20th century, parents and teachers forced kids to switch from left to right hand as they thought it was some kind of disease or disorder. Today, 10% of the world’s population is left-handed, and with time the superstitions have vanished. 

The difference between left-handed and right-handed people has caused many research and studies and every time a new conclusion arrives. Many people believed that left-handed people are more intellectual or their creative side is more dominant, but no experiment has proven it so far. Since many US presidents were left-handed, it got people thinking that they have better leadership qualities. 

Several studies have concluded that left-handed people are more prone to diseases like dyslexia and ADHD. Many studies are still going on to understand the genetics behind left-handed people. There are more than one genetic factors that are responsible for causing left-handedness. But, even if a child is left-handed during birth, their upbringing or training to make them right-handed can change the dominant hand. 

What is Right-Handed?

In right-handed people, the left side of the brain dominates as this side is responsible for controlling the right leg, hand, eye, etc. Many scientists perform studies to understand how ancestors became primarily right-handed even before the humans arrived. Evidence from 1.5 million years ago shows that Homohabilis and Home erectus showed right-handedness. 

One of the most common theories for right-handedness is brain lateralization that was further caused by vocalization. Cerebral asymmetry for speech is a process of evolution. When people started to use sounds and words to communicate, their hands were relieved from making gestures and thus more available for work like hunting and tool making. A study by McManus (1999, 2002) suggests that left-handedness is a result of mutation.

Today, 90% of the world’s population is right-handed. Evolution has caused our brain to differentiate activities and allot a specific side of the brain for that. But, studies show that the right-handed preference for manual actions are developed in fetus within 15 weeks as they start sucking their right thumb. 

Main Differences Between Left Handed and Right Handed

1. In left-handed people, their left hand is more dominant and in right-handed people their right hand is dominant.
2. About 10% population of the world are left-handed whereas the rest 90% population is right-handed. 
3. Left-handed people are more prone to diseases like dyslexia and ADHD where handedness doesn’t have that influence on right-handed people. 
4. Some everyday tasks like putting on a zipper, swiping credit cards, using computer mouse become difficult for left-handed people but not for right-handed people.
5. Left-handed people show less brain lateralization whereas right-handed people show more brain lateralization.
6. Some experts say that ultrasound has effects on causing left-handedness but it doesn’t have any effect on causing right-handedness. 
7. Left-handed parents are more likely to have left-handed children whereas right-handed parents don’t have much influence on the handedness of their children.

References

1. https://psycnet.apa.org/record/1978-00208-001
2. https://science.sciencemag.org/content/198/4317/631.abstract

Emma Smith holds an MA degree in English from Irvine Valley College. She has been a Journalist since 2002, writing articles on the English language, Sports, and Law. Read more about me on her bio page.

This article is about left- and right-handedness in humans. For physical objects which are “handed”, see Chirality. For other uses, see Handedness (disambiguation).

«Leftie» redirects here. For the political orientation, see Left-wing politics.

«Rightie» redirects here. For the political orientation, see Right-wing politics.

In human biology, handedness is an individual’s preferential use of one hand, known as the dominant hand, due to it being stronger, faster or more dextrous. The other hand, comparatively often the weaker, less dextrous or simply less subjectively preferred, is called the non-dominant hand.^[2][3][4] In a study from 1975 on 7,688 children in US grades 1-6, Left handers comprised 9.6% of the sample, with 10.5% of male children and 8.7% of female children being left-handed.^[5][6][7] Handedness is often defined by one’s writing hand, as it is fairly common for people to prefer to do a particular task with a particular hand. There are true ambidexterity (equal preference of either hand), but it is rare—most people prefer using one hand for most purposes.

Most of the current research suggests that left-handedness has an epigenetic marker—a combination of genetics, biology and the environment.

Because the vast majority of the population is right-handed, many devices are designed for use by right-handed people, making their use by left-handed people more difficult.^[8] In many countries, left-handed people are or were required to write with their right hands. Left-handed people are also more prone to certain health problems. However, left-handed people have an advantage in sports that involves aiming at a target in an area of an opponent’s control, as their opponents are more accustomed to the right-handed majority. As a result, they are over-represented in baseball, tennis, fencing, cricket, boxing,^[9][10] and mixed martial arts (MMA).^[11]

Types[edit]

• Right-handedness is the most common type. Right-handed people are more skillful with their right hands. Studies suggest that approximately 90% of people are right-handed.^[7][12]
• Left-handedness is less common. Studies suggest that approximately 10% of people are left-handed.^[7][13]
• Ambidexterity refers to having equal ability in both hands. Those who learn it still tend to favor their originally dominant hand. This is uncommon, with about a 1% prevalence.^[14]
• Mixed-handedness or cross-dominance is the change of hand preference between different tasks. This is very uncommon in the population with less than 1% prevalence. This cannot be learned and is highly associated with the person’s childhood brain development.^[15]

Measurement[edit]

Handedness may be measured behaviourally (performance measures) or through questionnaires (preference measures). The Edinburgh Handedness Inventory has been used since 1971 but contains many dated questions and is hard to score. The longer Waterloo Handedness Questionnaire is not widely accessible. More recently, the Flinders Handedness Survey (FLANDERS) has been developed.^[16]

Causes[edit]

There are several theories of how handedness develops.

Language dominance[edit]

One common handedness theory is the brain hemisphere division of labor. In most people, the left side of the brain controls speaking. The theory suggests it is more efficient for the brain to divide major tasks between the hemispheres—thus most people may use the non-speaking (right) hemisphere for perception and gross motor skills. As speech is a very complex motor control task, the specialised fine motor areas controlling speech are most efficiently used to also control fine motor movement in the dominant hand. As the right hand is controlled by the left hemisphere (and the left hand is controlled by the right hemisphere) most people are, therefore right-handed. The theory depends on left-handed people having a reversed organisation.^[17] However, the majority of left-handers have been found to have left-hemisphere language dominance—just like right-handers.^[18][19] Only around 30% of left-handers are not left-hemisphere dominant for language. Some of those have reversed brain organisation, where the verbal processing takes place in the right-hemisphere and visuospatial processing is dominant to the left hemisphere.^[20] Others have more ambiguous bilateral organisation, where both hemispheres do parts of typically lateralised functions. When tasks designed to investigate lateralisation (preference for handedness) are averaged across a group of left-handers, the overall effect is that left-handers show the same pattern of data as right-handers, but with a reduced asymmetry.^[21] This finding is likely due to the small proportion of left-handers who have atypical brain organisation.

Genetic factors[edit]

Handedness displays a complex inheritance pattern. For example, if both parents of a child are left-handed, there is a 26% chance of that child being left-handed.^[22] A large study of twins from 25,732 families by Medland et al. (2006) indicates that the heritability of handedness is roughly 24%.^[23]

Two theoretical single-gene models have been proposed to explain the patterns of inheritance of handedness, by Marian Annett^[24] of the University of Leicester, and by Chris McManus^[22] of UCL.

However, growing evidence from linkage and genome-wide association studies suggests that genetic variance in handedness cannot be explained by a single genetic locus.^{[25][26][27][28][29][30][31][32][excessive citations]} From these studies, McManus et al. now conclude that handedness is polygenic and estimate that at least 40 loci contribute to the trait.^[33]

Brandler et al. performed a genome-wide association study for a measure of relative hand skill and found that genes involved in the determination of left-right asymmetry in the body play a key role in handedness.^[34] Brandler and Paracchini suggest the same mechanisms that determine left-right asymmetry in the body (e.g. nodal signaling and ciliogenesis) also play a role in the development of brain asymmetry
(handedness being a reflection of brain asymmetry for motor function).^[35]

In 2019, Wiberg et al. performed a genome-wide association study and found that handedness was significantly associated with four loci, three of them in genes encoding proteins involved in brain development.^[36]

Epigenetic factors[edit]

Twin studies indicate that genetic factors explain 25% of the variance in handedness, and environmental factors the remaining 75%.^[37] While the molecular basis of handedness epigenetics is largely unclear, Ocklenburg et al. (2017) found that asymmetric methylation of CpG sites plays a key role for gene expression asymmetries related to handedness.^[38][39]

Prenatal hormone exposure[edit]

Four studies have indicated that individuals who have had in-utero exposure to diethylstilbestrol (a synthetic estrogen based medication used between 1940 and 1971) were more likely to be left-handed over the clinical control group. Diethylstilbestrol animal studies «suggest that estrogen affects the developing brain, including the part that governs sexual behavior and right and left dominance».^{[40][41][42][43]}

Prenatal vestibular asymmetry[edit]

Previc, after reviewing a large number of studies, found evidence that the position of the fetus in the final trimester and a baby’s subsequent birth position can affect handedness. About two-thirds of fetuses present with their left occiput (back of the head) at birth. This partly explains why prematurity results in a decrease in right-handedness. Previc argues that asymmetric prenatal positioning creates asymmetric stimulation of the vestibular system, which is involved in the development of handedness. In fact, every major disorder in which patients show reduced right-handedness is associated with either vestibular abnormalities or delay,^[44] and asymmetry of the vestibular cortex is strongly correlated with the direction of handedness.^[45]

Ultrasound[edit]

Another theory is that ultrasound may sometimes affect the brains of unborn children, causing higher rates of left-handedness in children whose mothers receive ultrasound during pregnancy. Research suggests there may be a weak association between ultrasound screening (sonography used to check the healthy development of the fetus and mother) and left-handedness.^[46]

Developmental timeline [edit]

Researchers studied fetuses in utero and determined that handedness in the womb was a very accurate predictor of handedness after birth.^[47] In a 2013 study, 39% of infants (6 to 14 months) and 97% of toddlers (18 to 24 months) demonstrated a hand preference.^[48]

Infants have been observed to fluctuate heavily when choosing a hand to lead in grasping and object manipulation tasks, especially in one- versus two-handed grasping. Between 36 and 48 months, there is a significant decline in variability between handedness in one-handed grasping; it can be seen earlier in two-handed manipulation. Children of 18–36 months showed more hand preference when performing bi-manipulation tasks than with simple grasping.^[49]

The decrease in handedness variability in children of 36–48 months may be attributable to preschool or kindergarten attendance due to increased single-hand activities such as writing and coloring.^[49] Scharoun and Bryden noted that right-handed preference increases with age up to the teenage years.^[6]

Recently, studies have shown that left-handers and right-handers differ in their growth trajectory, i.e., among kindergarten children left-handers have longer digit length whereas among adults left -handers have shorter digit lengths.^[50]

Correlation with other factors[edit]

Intelligence[edit]

In his book Right-Hand, Left-Hand, Chris McManus of University College London argues that the proportion of left-handers is increasing, and that an above-average quota of high achievers have been left-handed. He says that left-handers’ brains are structured in a way that increases their range of abilities, and that the genes that determine left-handedness also govern development of the brain’s language centers.^[51]

Writing in Scientific American, he states:

Studies in the U.K., U.S. and Australia have revealed that left-handed people differ from right-handers by only one IQ point, which is not noteworthy … Left-handers’ brains are structured differently from right-handers’ in ways that can allow them to process language, spatial relations and emotions in more diverse and potentially creative ways. Also, a slightly larger number of left-handers than right-handers are especially gifted in music and math. A study of musicians in professional orchestras found a significantly greater proportion of talented left-handers, even among those who played instruments that seem designed for right-handers, such as violins. Similarly, studies of adolescents who took tests to assess mathematical giftedness found many more left-handers in the population.^[52]

Left-handers are overrepresented among those with lower cognitive skills and mental impairments, with those with intellectual disability (ID) being roughly twice as likely to be left-handed, as well as generally lower cognitive and non-cognitive abilities amongst left-handed children.^[53] Left-handers are nevertheless also overrepresented in high IQ societies, such as Mensa. A 2005 study found that «approximately 20% of the members of Mensa are lefthanded, double the proportion in most general populations».^[54]

Ghayas & Adil (2007) found that left-handers were significantly more likely to perform better on intelligence tests than right-handers and that right-handers also took more time to complete the tests.^[55] In a systematic review and meta-analysis, Ntolka & Papadatou-Pastou (2018) found that right-handers had higher IQ scores, but that difference was negligible (about 1.5 points).^[56]

The prevalence of difficulties in left-right discrimination was investigated in a cohort of 2,720 adult members of Mensa and Intertel by Storfer.^[57] According to the study, 7.2% of the men and 18.8% of the women evaluated their left-right directional sense as poor or below average; moreover participants who were relatively ambidextrous experienced problems more frequently than did those who were more strongly left- or right-handed.^[57] The study also revealed an effect of age, with younger participants reporting more problems.^[57]

Early childhood intelligence[edit]

Nelson, Campbell, and Michel studied infants and whether developing handedness during infancy correlated with language abilities in toddlers. In the article they assessed 38 infants and followed them through to 12 months and then again once they became toddlers from 18 to 24 months. They discovered that when a child developed a consistent use of their right or left hand during infancy (such as using the right hand to put the pacifier back in, or grasping random objects with the left hand), they were more likely to have superior language skills as a toddler. Children who became lateral later than infancy (i.e., when they were toddlers) showed normal development of language and had typical language scores.^[58] The researchers used Bayley scales of infant and toddler development to assess all the subjects.

Music[edit]

In two studies, Diana Deutsch found that left-handers, particularly those with mixed hand preference, performed significantly better than right-handers in musical memory tasks.^[59][60] There are also handedness differences in perception of musical patterns. Left-handers as a group differ from right-handers, and are more heterogeneous than right-handers, in perception of certain stereo illusions, such as the octave illusion, the scale illusion, and the glissando illusion.^[61]

Health[edit]

Studies have found a positive correlation between left-handedness and several specific physical and mental disorders and health problems, including:

• Lower-birth-weight and complications at birth are positively correlated with left-handedness.^[62]
• A variety of neuropsychiatric and developmental disorders like autism spectrum disorders, depression, bipolar disorder, anxiety disorders, schizophrenia, and alcoholism have been associated with left- and mixed-handedness.^[39][63]
• A 2012 study showed that nearly 40% of children with cerebral palsy were left-handed,^[64] while another study demonstrated that left-handedness was associated with a 62% increased risk of Parkinson’s disease in women, but not in men.^[65] Another study suggests that the risk of developing multiple sclerosis increases for left-handed women, but the effect is unknown for men at this point.^[66] Other studies also show that left-handers are more predisposed to manic depression and are three times more likely than right-handers to commit suicide.^[67]
• Left-handed women may have a higher risk of breast cancer than right-handed women and the effect is greater in post-menopausal women.^[68]
• At least one study maintains that left-handers are more likely to suffer from heart disease, and are more likely to have reduced longevity from cardiovascular causes.^[69]
• Left-handers may be more likely to suffer bone fractures.^[70]
• Left-handers have a lower prevalence of arthritis and ulcer, while they also recover more quickly from strokes than right-handers.^[71]
• One systematic review concluded: «Left-handers showed no systematic tendency to suffer from disorders of the immune system».^[72]

As handedness is a highly heritable trait associated with various medical conditions, and because many of these conditions could have presented a Darwinian fitness challenge in ancestral populations, this indicates left-handedness may have previously been rarer than it currently is, due to natural selection. However, on average, left-handers have been found to have an advantage in fighting and competitive, interactive sports, which could have increased their reproductive success in ancestral populations.^[73]

Income[edit]

In a 2006 U.S. study, researchers from Lafayette College and Johns Hopkins University concluded that there was no statistically significant correlation between handedness and earnings for the general population, but among college-educated people, left-handers earned 10 to 15% more than their right-handed counterparts.^[74]

In a 2014 study published by the National Bureau of Economic Research, Harvard economist Joshua Goodman finds that left-handed people earn 10 to 12 percent less over the course of their lives than right-handed people. Goodman attributes this disparity to higher rates of emotional and behavioral problems in left-handed people.^[53]

Left-handedness and sports[edit]

Interactive sports such as table tennis, badminton and cricket have an overrepresentation of left-handedness, while non-interactive sports such as swimming show no overrepresentation. Smaller physical distance between participants increases the overrepresentation. In fencing, about half the participants are left-handed.^[75] In tennis, 40% of the seeded players are left-handed.^[67] The term southpaw is sometimes used to refer to a left-handed individual, especially in baseball and boxing.^[76] Some studies suggest that right handed male athletes tend to be statistically taller and heavier than left handed ones.^[77]

Other, sports-specific factors may increase or decrease the advantage left-handers usually hold in one-on-one situations:

• In cricket, the overall advantage of a bowler’s left-handedness exceeds that resulting from experience alone: even disregarding the experience factor (i.e., even for a batsman whose experience against left-handed bowlers equals his experience against right-handed bowlers), a left-handed bowler challenges the average (i.e., right-handed) batsman more than a right-handed bowler does, because the angle of a bowler’s delivery to an opposite-handed batsman is much more penetrating than that of a bowler to a same-handed batsman (see Wasim Akram).^{[citation needed]}
• In baseball, a right-handed pitcher’s curve ball will break away from a right-handed batter and towards a left-handed batter. While studies of handedness show that only 10% of the general population is left-handed, the proportion of left-handed MLB players is closer to 39% of hitters and 28% of pitchers, according to 2012 data.^[78] Historical batting averages show that left-handed batters have a slight advantage over right-handed batters when facing right-handed pitchers.^[79] Because there are fewer left-handed pitchers than right-handed pitchers, left-handed batters have more opportunities to face right-handed pitchers than their right-handed counterparts have against left-handed pitchers.^[80] Fourteen of the top twenty career batting averages in Major League Baseball history have been posted by left-handed batters.^[81] Left-handed batters have a slightly shorter run from the batter’s box to first base than right-handers. This gives left-handers a slight advantage in beating throws to first base on infield ground balls. Perhaps more importantly, the follow through of a left-handed swing provides momentum in the direction of first base, while the right handed batter must overcome the swing momentum towards third base before beginning his run.^{[citation needed]}
  • Because a left-handed pitcher faces first base when he is in position to throw to the batter, whereas a right-handed pitcher has his back to first base, a left-handed pitcher has an advantage when attempting to pick off baserunners at first base.^[82]
  • Defensively in baseball, left-handedness is considered an advantage for first basemen because they are better suited to fielding balls hit in the gap between first and second base, and because they do not have to pivot their body around before throwing the ball to another infielder.^[83] For the same reason, the other infielder’s positions are seen as being advantageous to right-handed throwers. Historically, there have been few left-handed catchers because of the perceived disadvantage a left-handed catcher would have in making the throw to third base, especially with a right-handed hitter at the plate.^[84] A left-handed catcher would have a potentially more dangerous time tagging out a baserunner trying to score.^[84] With the ball in the glove on the right hand, a left-handed catcher would have to turn his body to the left to tag a runner. In doing so, he can lose the opportunity to brace himself for an impending collision.^[84] On the other hand, the Encyclopedia of Baseball Catchers states:^[84]

One advantage is a left-handed catcher’s ability to frame a right-handed pitcher’s breaking balls. A right-handed catcher catches a right-hander’s breaking ball across his body, with his glove moving out of the strike zone. A left-handed catcher would be able to catch the pitch moving into the strike zone and create a better target for the umpire.

• In four wall handball, typical strategy is to play along the left wall forcing the opponent to use their left hand to counter the attack and playing into the strength of a left-handed competitor.
• In handball, left-handed players have an advantage on the right side of the field when attacking, getting a better angle, and that defenders might be unused to them. Since few people are left-handed, there is a demand for such players.
• In water polo, the centre forward position has an advantage in turning to shoot on net when rotating the reverse direction as expected by the centre of the opposition defence and gain an improved position to score. Left-handed drivers are usually on the right side of the field, because they can get better angles to pass the ball or shoot for goal.
• Ice hockey typically uses a strategy in which a defence pairing includes one left-handed and one right-handed defender. A disproportionately large number of ice hockey players of all positions, 62 percent, shoot left, though this does not necessarily indicate left-handedness.^[85]
• In American football, the handedness of a quarterback affects blocking patterns on the offensive line. Tight ends, when only one is used, typically line up on the same side as the throwing hand of the quarterback, while the offensive tackle on the opposite hand, which protects the quarterback’s «blind side,» is typically the most valued member of the offensive line. Receivers also have to adapt to the opposite spin.^[86] While uncommon, there have been several notable left-handed quarterbacks.
• In bowling, the oil pattern used on the bowling lane breaks down faster the more times a ball is rolled down the lane. Bowlers must continually adjust their shots to compensate for the ball’s change in rotation as the game or series is played and the oil is altered from its original pattern. A left-handed bowler competes on the opposite side of the lane from the right-handed bowler and therefore deals with less breakdown of the original oil placement. This means left-handed bowlers have to adjust their shot less frequently than right-handed bowlers in team events or qualifying rounds where there are possibly 4-10 people per set of two lanes. This can allow them to stay more consistent. However, this advantage is not present in bracket rounds and tournament finals where matches are 1v1 on a pair of lanes.

Sex[edit]

According to a meta-analysis of 144 studies, totaling 1,787,629 participants, the best estimate for the male to female odds ratio was 1.23, indicating that men are 23% more likely to be left-handed. For example, if the incidence of female left-handedness was 10%, then the incidence of male left-handedness would be approximately 12% (10% incidence of left-handedness among women multiplied by an odds ratio of 1:1.23 for women:men results in a 12.3% incidence of left-handedness among men).^{[87][clarification needed]}

Sexuality and gender identity[edit]

Some studies examining the relationship between handedness and sexual orientation have reported that a disproportionate minority of homosexual people exhibit left-handedness,^[88] though findings are mixed.^[89][90][91]

A 2001 study also found that males whose gender identity did not align with their sex assigned at birth, were more than twice as likely to be left-handed than a clinical control group (19.5% vs. 8.3%, respectively).^[92]

Paraphilias (atypical sexual interests) have also been linked to higher rates of left-handedness. A 2008 study analyzing the sexual fantasies of 200 males found «elevated paraphilic interests were correlated with elevated non-right handedness».^[93] Greater rates of left-handedness have also been documented among pedophiles.^{[94][95][96][97]}

A 2014 study attempting to analyze the biological markers of asexuality asserts that non-sexual men and women were 2.4 and 2.5 times, respectively, more likely to be left-handed than their heterosexual counterparts.^[98]

Mortality rates in combat[edit]

A study at Durham University—which examined mortality data for cricketers whose handedness was a matter of public record—found that left-handed men were almost twice as likely to die in war as their right-handed contemporaries.^[99] The study theorised that this was because weapons and other equipment was designed for the right-handed. “I can sympathise with all those left-handed cricketers who have gone to an early grave trying desperately to shoot straight with a right-handed Lee Enfield .303,” wrote a journalist reviewing the study in the cricket press.^[100] The findings echo those of previous American studies, which found that left-handed US sailors were 34% more likely to have a serious accident than their right-handed counterparts.^[101]

Episodic memory[edit]

A high level of handedness (whether strongly favoring right or left) is associated with poorer episodic memory,^[102][103] and with poorer communication between brain hemispheres,^[104] which may give poorer emotional processing, although bilateral stimulation may reduce such effects.^[105][106]

Corpus callosum[edit]

A high level of handedness is associated with a smaller corpus callosum whereas low handedness with a larger one.^[107]

Divergent thinking[edit]

Left-handedness is associated with better divergent thinking.^[108]

In culture[edit]

Many tools and procedures are designed to facilitate use by right-handed people, often without realizing the difficulties incurred by the left-handed. John W. Santrock has written, «For centuries, left-handers have suffered unfair discrimination in a world designed for right-handers.»^[8]

As a child, British king George VI (1895–1952) was naturally left-handed. He was forced to write with his right hand, as was common practice at the time. He was not expected to become king, so that was not a factor.^[109] McManus noted that, as the Industrial Revolution spread across Western Europe and the United States in the 19th century, workers needed to operate complex machines that were designed with right-handers in mind. This would have made left-handers more visible and at the same time appear less capable and more clumsy. During this era, children were taught to write with a dip pen. While a right-hander could smoothly drag the pen across paper from left to right, a dip pen could not easily be pushed across by the left hand without digging into the paper and making blots and stains.^[110]

Negative connotations and discrimination[edit]

Moreover, apart from inconvenience, left-handed people have historically been considered unlucky or even malicious for their difference by the right-handed majority. In many languages, including English, the word for the direction «right» also means «correct» or «proper». Throughout history, being left-handed was considered negative, or evil; even into the 20th century, left-handed children were beaten by schoolteachers for writing with their left hand.

The Latin adjective sinister means «left» as well as «unlucky», and this double meaning survives in European derivatives of Latin, including the English words «sinister» (meaning both ‘evil’ and ‘on the bearer’s left on a coat of arms’) and «ambisinister» meaning ‘awkward or clumsy with both or either hand’.

There are many negative connotations associated with the phrase «left-handed»: clumsy, awkward, unlucky, insincere, sinister, malicious, and so on. A «left-handed compliment» is one that has two meanings, one of which is unflattering to the recipient. In French, gauche means both «left» and «awkward» or «clumsy», while droit(e) (cognate to English direct and related to «adroit») means both «right» and «straight», as well as «law» and the legal sense of «right». The name «Dexter» derives from the Latin for «right», as does the word «dexterity» meaning manual skill. As these are all very old words, they would tend to support theories indicating that the predominance of right-handedness is an extremely old phenomenon.

Black magic is sometimes referred to as the «left-hand path».

Until very recently in Taiwan (and still in Mainland China, Japan and both North and South Korea), left-handed people were forced to switch to being right-handed, or at least switch to writing with the right hand. Due to the importance of stroke order, developed for the comfortable use of right-handed people, it is considered more difficult to write legible Chinese characters with the left hand than it is to write Latin letters, though difficulty is subjective and depends on the writer.^[111] Because writing when moving one’s hand away from its side towards the other side of the body can cause smudging if the outward side of the hand is allowed to drag across the writing, writing in the Latin alphabet might possibly be less feasible with the left hand than the right under certain circumstances. Conversely, right-to-left alphabets, such as the Arabic and Hebrew, are generally considered easier to write with the left hand in general.^{[citation needed]} Depending on the position and inclination of the writing paper, and the writing method, the left-handed writer can write as neatly and efficiently or as messily and slowly as right-handed writers. Usually the left-handed child needs to be taught how to write correctly with the left hand, since discovering a comfortable left-handed writing method on one’s own may not be straightforward.^[112][113]

In the Soviet Union, all left-handed children were forced to write with their right hand in the Soviet school system.^[114][115]

International Left-Handers Day[edit]

International Left-Handers Day is held annually every August 13.^[116] It was founded by the Left-Handers Club in 1992, with the club itself having been founded in 1990.^[116] International Left-Handers Day is, according to the club, «an annual event when left-handers everywhere can celebrate their sinistrality (left-handedness) and increase public awareness of the advantages and disadvantages of being left-handed.»^[116] It celebrates their uniqueness and differences, who are from seven to ten percent of the world’s population. Thousands of left-handed people in today’s society have to adapt to use right-handed tools and objects. Again according to the club, «in the U.K. alone there were over 20 regional events to mark the day in 2001 – including left-v-right sports matches, a left-handed tea party, pubs using left-handed corkscrews where patrons drank and played pub games with the left hand only, and nationwide ‘Lefty Zones’ where left-handers’ creativity, adaptability and sporting prowess were celebrated, whilst right-handers were encouraged to try out everyday left-handed objects to see just how awkward it can feel using the wrong equipment.»^[116]

In other animals[edit]

Kangaroos and other macropod marsupials show a left-hand preference for everyday tasks in the wild. ‘True’ handedness is unexpected in marsupials however, because unlike placental mammals, they lack a corpus callosum. Left-handedness was particularly apparent in the red kangaroo (Macropus rufus) and the eastern gray kangaroo (Macropus giganteus). Red-necked (Bennett’s) wallabies (Macropus rufogriseus) preferentially use their left hand for behaviours that involve fine manipulation, but the right for behaviours that require more physical strength. There was less evidence for handedness in arboreal species.^[117] Studies of dogs, horses, and domestic cats have shown that females of those species tend to be right-handed, while males tend to be left-handed.^[118]

See also[edit]

General[edit]

• Cardinal direction
• Clockwise, which also discusses counterclockwise/anticlockwise, the two terms for the opposite sense of rotation
• Dexter and sinister
• Footedness
• Laterality
• List of left-handed presidents of the United States
• Left- and right-hand traffic
• Ocular dominance (eyedness)
• Proper right and proper left
• Relative direction

Handedness[edit]

• Edinburgh Handedness Inventory
• Geschwind–Galaburda hypothesis
• Neuroanatomy of handedness
• Situs inversus
• Twins and handedness

References[edit]

External links[edit]

• Lefties Have The Advantage In Adversarial Situations, ScienceDaily, April 14, 2006.
• Science Creative Quarterly’s overview of some of the genetic underpinnings of left-handedness
• A left-handed senior citizen recalls the emotional torment he faced at a New York public school in the 1920s. (Audio slideshow)
• Woznicki, Katrina (2005). «Breast Cancer Risk Doubles for Southpaw Women», MedPage Today, 26 September.
• Hansard (1998). «Left-handed Children», Debate contribution by the Rt Hon. Mr. Peter Luff (MP for Mid-Worcestershire), House of Commons, 22 July.
• Is your Child Left-Handed? Why, according to psychological tests, left-handed people ought to remain so. Popular Science. December 1918. p. 22.
• Handedness and Earnings / Higher paychecks: a left-handed compliment?
• Handedness & earnings, published in Journal of Human Resources 2007
• Handedness Research Institute
• Study Reveals Why Lefties Are Rare

На основании Вашего запроса эти примеры могут содержать грубую лексику.

На основании Вашего запроса эти примеры могут содержать разговорную лексику.

At the outset, they have equal amounts of left and right-handed amino acids.

Изначально существует равное количество левых и правых аминокислот.

It turns out that including left and right-handed 4×4 quaternion matrices is equivalent to including a single right-multiplication by a unit quaternion which adds an extra SU(2) and so has an extra neutral boson and two more charged bosons.

Оказывается, что включение левых и правых 4× 4 матриц кватернионов эквивалентно включению одного правого умножения на единичный кватернион, который добавляет дополнительный SU(2) и так далее имеет дополнительный нейтральный бозон и еще два заряженных бозона.

Each one of you will be giving us a sample of your handwriting, left and right-handed.

Very light and easy to use, this device is designed for both left and right-handed use.

Очень легкий и простой в использовании, это устройство предназначено как для левой и правой рукой.

Note that the neutral electroweak Z boson couples to left and right-handed fermions.

Заметим, что нейтральный электрослабый Z-бозон связан с левыми и правыми фермионами.

But ordinary undirected chemistry, as in the hypothetical primordial soup, would produce equal mixtures of left and right-handed molecules, called racemates.

Однако в обычной химии, как в гипотетическом «первичном бульоне», должно было бы зарождаться равное количество лево- и правосторонних молекул, так называемый рацемат.

Just as there are left and right-handed humans, elephants also prefer to use either the left or the right tusk.

Подобно тому, как люди делятся на правшей и левшей, слоны также предпочитают использовать левый или правый бивень.

For example, the quarks and leptons in these solutions come in left and right-handed versions, as they do in our universe.

Например, кварки и лептоны в этих решениях имеют левую и правую версии, как и в нашей Вселенной.

Moreover, the amino acids produced were in any case what is known as a racemic (50:50) mixture of left and right-handed forms, whereas all living plants and animals can only use left-handed amino acids to make proteins.

В любом случае полученные аминокислоты были рацемической (50:50) смесью из правосторонних и левосторонних форм, тогда как для образования белков все живые растения и животные используют только левосторонние аминокислоты.

Life on Earth uses left-handed amino acids, and they are never mixed with right-handed ones, but the amino acids found in the meteorite had equal amounts of the left and right-handed varieties. (read more)

Земле живые организмы использует левые аминокислоты, и не зафиксировано их смешивание с правыми, но аминокислоты, найденные в метеоритах (и левые, и правые) были в равном соотношении и количестве.

Left and right-handed molecules.

Ничего не найдено для этого значения.

Результатов: 11. Точных совпадений: 11. Затраченное время: 40 мс

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Индекс слова: 1-300, 301-600, 601-900

Индекс выражения: 1-400, 401-800, 801-1200

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Are you a lefty or a righty? No matter what your answer is, it will certainly be given with a lot of confidence because we are talking about something that feels very natural to you. It feels as natural as doing most of your daily routine with the other hand may feel unnatural. But have you even wondered what determines the use of one hand over the other?

Definitions

Left-handed people use their left hand for most of their daily tasks. In many cultures, being a left-handed person used to be regarded as being generally clumsy. The word “lefty” can even have this negative meaning in many languages. Even so, lefties make for good sportsmen, great artists, most US presidents, and they even get their own day on August 13^th. Roughly one person in ten is left handed meaning that 10% of the Earth’s population is left handed. Also, studies have shown that there are more left-handed men than women.

It is said that since our brain’s hemispheres are crossed (the right side of the brain controls the left part of the body and the left side of the brain controls the right side), lefties are more prone to having the characteristics dictated by the right side of the brain. This means that they should be more creative, more intuitive, better at expressing their feelings, better at visualization and 3D perception. Also, the dominance of the right side of the brain and a prevalence of emotional intellect could make lefties more susceptible to a wider range of emotions, meaning that they live more intensely. Studies regarding the dominance of the right brain and these characteristics of left-handed people are not yet conclusive in all aspects.

Right-handed people make up the majority or 90% of the entire human population. They are said to be left-brained, meaning that they will have higher abilities in mathematics, logical thinking and organizing, memorizing, computing and technical information processing, discovering patterns and applying them. The world is built around right handed dominance. Even the expression of “being one’s right hand” is illustrative in this respect. In terms of religion, Christianity is most biased in this respect as the sign of the cross can only be made with the right hand and the right hand alone can be placed on the Bible when being sworn in.

So what is the difference between left-handed and right-handed people?

Apart from the fact that they each use a different dominant hand, we can say the deduced differences can be those resulting from the use of the corresponding brain hemisphere. We say that left-handed people are more creative, more emotional and better at sports than right-handed people are. In the case of the latter, it is mainly because left-handed people compete against right-handed people more often, which makes for great exercise. They can also switch hands during the game, which can put off the opponent.

Left-handed people have a tough life living in a world designed for the 90% of right-handed people. This means that most items, tools and gadgets are created for right handed users. However, there are industries which take notice of their left-handed customers and make special items for them, guitars and watches, for example.

Not so long ago teachers in school considered left-handedness a handicap and would try to correct it. But the years have shown that forcing left-handed children to use their right hand has traumatic long-term effects such as poor concentration, bad memory, physical tiredness, bad handwriting, stuttering, nail-biting, etc. All this was due to coercion which disregarded the natural cross-wiring of the brain and a situation in which the child did not feel natural and at ease.

Comparison Chart

Left-handed people	Right handed people
Use their left hand as a dominant hand	Use their right hand as a dominant hand
Make up 10% of the Earth’s population	Make up 90% of the Earth’s population
The right hemisphere of the brain is dominant	The left hemisphere of the brain is dominant
Should not be forced to use the other hand	Should not be forced to use the other hand
There are special items created for left-handed people	Most items are created for right-handed people