left handed

from Wikipedia, the free encyclopedia
A left-handed person when writing

Left-handers prefer to use their left hand, especially for activities that place high demands on fine motor skills, strength or speed (e.g. for writing or throwing). The handedness , i.e. the preference of the right or left hand, is explained by the dominance of the opposite hemisphere. It is not yet clear whether left-handedness (including sinistrality ) is an innate predisposition. While left-handed children were re-educated into the 1970s, this is not done today, as re-education can cause serious damage to development.

background

The dominance of one hand

In humans, one hand is dominant ( handedness phenomenon ). Since each hemisphere of the brain has its specific part in information processing, this is also known as functional asymmetry. Each half of the brain is connected to the opposite half of the body via main nerve cords and controls them. In the case of left-handedness, the right hemisphere can be assumed to play a leading role.

The dominant hand can act faster, more precisely, more strongly. Especially when a spontaneous reaction is required and for activities that are associated with special cognitive performance. But that doesn't mean that one hand can do everything and the other cannot do anything. Rather, the hands have specific areas of responsibility that complement each other. This specialization is also referred to by scientists as "two-handed higher order":

  • dominant = main actor, quick reaction, special fine motor skills and dexterity
  • non-dominant = preparing and accompanying the action, active holding functions

It is largely unclear why right-handed people are in the majority in all cultures - despite various theories. Presumably, social factors are just as involved as the functional structure of the brain.

Share of left-handers

Statistics indicate the proportion of left-handers in the population at 10 to 15 percent. It should be noted that the value for surveys is lower than for targeted tests, which is due to the long-term re-education of children and their imitation of adults. Accordingly, left-handers are significantly less common among old people in statistics.

Estimates of the theoretical frequency of left-handed people in the absence of conscious or unconscious re-education go up to half the population. In certain sports (e.g. water polo), the proportion of left-handers is around 30% (handball 25%), since left-handers are specifically searched for in a position-specific manner and tests are also used to identify natural left-handers, as these are easier to play with let sport-specific left-handers back to school as real right-handers.

Determination of the individual handedness

In most children, by observing spontaneous actions and reflexes, the clear preference for one hand can be recognized early on. Children should not be influenced when trying out and exploring the abilities of both hands. The individual handedness consolidates during the first years of life.

When you start school, the handedness should be decided, because repositioning the writing hand several times is disadvantageous for the development. In unclear cases, specific tests can help. You will e.g. B. offered by advice centers for left-handers or by occupational therapists with the appropriate qualifications. A scientific evaluation, however, only makes sense from the age of six using a hand dominance test. Children have to trace and puncture different contours one after the other with both hands. Simpler but less informative tests such as the clap or grip test can be carried out at an earlier age.

If an originally left-handed predisposition is only recognized later, there are now procedures for careful retraining with the help of professional left-handed advisors.

Left-handed writing

Today, the school guidelines of almost all German education ministries state that existing left-handed people must not be changed. Left-handed children should experience their disposition as natural and equal.

Writing beginners need special methodical support, especially when learning the right writing posture. Particularly important aspects are:

  • Direction of writing : The natural direction of gaze and writing of many left-handers is from right to left. During the first writing and reading exercises, letters, syllables or numbers and the use of mirror writing can therefore occur. However, this is usually a temporary phenomenon.
  • Pen and paper position : It is recommended to observe the following ergonomic writing position: The paper is a little to the left of the middle of the body and is turned slightly clockwise. The end of the pen points roughly to the left shoulder. The hand always stays below the writing line. This allows relaxed writing without smudging the ink. A special writing pad is also available with marking of the correct position of the paper. Sometimes left-handed people also have a hook-shaped or inverted writing position. The more strongly angled hand is guided above the writing line. In terms of ergonomics, however, this posture is less favorable.
  • Selection of writing materials : Fountain pens for left-handers (with a specific handle shape and nib) are offered by several companies. The width of the nib should be selected individually. It must be easy to push and pull, but not release too much ink (quick drying). In some schools an ink pen is allowed instead of the fountain pen, which is more practical for some left-handers. In everyday school life, other specific left-handed products can be useful, e.g. B. Sharpener, ruler, left-handed spiral pad, etc. So measuring with the ruler causes difficulties for left-handed people, because it is a mirror image of his intuitive direction of movement: He intuitively draws the line from right to left instead of left to right!
  • Sitting position : No right-writing child should sit to the left of the pupil, otherwise the freedom of movement of the writing arm is restricted for both of them. The board should be viewed straight ahead or by turning the body to the right. The incidence of light is best from the right or from the front.

Shorthand : In order to accommodate the natural sequence of movements of left-handers, the stenography system stepography was adapted to the needs of left-handers by mirroring this shorthand and thus writing it from right to left.

Many left-handers find switching to typing on a computer keyboard a relief.

Some left-handed people can spontaneously write mirror writing. The extent to which this ability depends on whether or not they have been reeducated is controversial in research. This so-called Leonardo phenomenon can also be observed in some cases in people who do not see themselves as left-handers, but it is usually assigned to left-handers.

Re-education and possible consequential problems

Since right-handedness is the norm in our society, left-handed people were usually forced to use their right hand as a writing hand until the 1970s at the latest when they started school. The psychologist Johanna Barbara Sattler describes the re-education of handedness as one of the “most massive bloodless interventions in the human brain”. She believes that forced retraining of left-handers can lead to serious problems such as poor concentration, memory disorders, dyslexia and language disorders such as: B. Word-finding disorders. If a person suffers from one of these problems, there are often psychological consequences that can range from poor self-confidence to serious behavioral disorders. In psychotherapeutic practice, the consequences of psychological retraining are not yet adequately addressed, since specialized therapists are still seldom to be found.

Even nowadays it is still common practice in many places to re-educate left-handed people, as the neural connections and the psychological and cognitive consequences of re-education are not yet sufficiently well known in the population. Some still believe that it is easier for a left-hander in a world of right-handers if he is trained right away.

More often, however, re-education has cultural causes (for example, the right hand used to greet people). This applies worldwide: Left-handedness is considered a serious stigma in Arab cultures and in Islamic countries . The reasons for this lie many centuries in the past and are partly of a pragmatic nature: In Arab (Islamic) and other cultures, cleaning after defecation is usually carried out (for right-handed people) with the bare left hand and water. This led to the left hand being considered unclean; it is therefore not used for eating or socializing.

Even with re-education, the left-handed person does not become a right-handed person. Only other areas of the brain take over control of the musculoskeletal system.

Self-retraining - unnoticed by imitation

There are left-handed children who decide to use their right hand for drawing and painting even in kindergarten. The cause is the very natural need to adapt at this age. Affected are the particularly attentive children who have not escaped the fact that they spontaneously prefer the other hand to their friends and caregivers and who find this uncomfortable. They then sometimes appear with both hands and later learn to write with the right hand. Usually neither the parents nor the educators notice what is happening. This self-retraining can have very similar consequences for the person concerned as a forced retraining. Because the handedness established in the brain does not change even if you retrain yourself. The person concerned is a retrained left-hander with a corresponding cerebral strain that can be felt for a lifetime.

Left-handedness in everyday life, hobbies and work

Even if left-handedness is accepted as a natural predisposition today, there are numerous aspects in a standardized right-handed environment in which left-handed people have to adapt or rethink. Structures, products, processes and devices are almost always designed for right-handers. It is true that left-handers are more flexible in thinking and acting as a result, but the fact that left-handers are largely not taken into account is often perceived as discrimination.

In the meantime, the specific requirements of left-handers are being given greater attention in individual areas. Left-handed products can make everyday life easier, but are often more expensive and difficult to obtain. The more precise, demanding and long-lasting an activity is, the more helpful such products can be.

Tools and everyday objects

For school and everyday life

Some kitchen tools for left-handers
Left handed scissors
Right handed scissors
Special feature of a) right-handed and c) left-handed knife
  • For school use, fountain pens, rulers, sharpeners and spiral pads are available for left-handers. It is particularly important that both the nib and the recessed grips are designed for left-handed writing on the fountain pen (see also the section on "Left-handed writing").
  • Computer mice : Unfavorable for left-handers are computer mice whose shape is particularly adapted to the ergonomics of the right hand. Symmetrically shaped mice can usually be operated left-handed without any problems, possibly with a change in the key assignment. Many left-handers use computer mice just like right-handers use their right hand. You can also train yourself relatively easily between right and left-handed mouse use.
  • Scissors : The critical point with scissors is the arrangement of the blades. In order to be able to cut precisely, the inside of the upper cutting edge must face the eye, otherwise you have to bend over the blade to see the cutting line clearly. This arrangement also accommodates the anatomy of the human hand: the blades are pressed together when cutting, whereas they are more likely to be pushed apart when the arrangement is reversed. In addition, the finger holes are often ergonomically adapted to the shape of the right hand. There are left-handed scissors in specialist retailers and left-handed shops, and now there are also robust tools such as sheet metal or tree scissors with adapted handles.
  • Knives : High-quality knives for soft cuttings, especially bread knives, are flat on the side facing the cuttings and have their cut (also serrated edge) exclusively on the open side. For right-handers, the left side is flat, so that the cut part is bent away to the right and the rest of the clippings remain flat. With mirror-inverted use by left-handers, straight cutting is hardly possible. That is why there are special left-handed knives with an opposing cut.
  • Other asymmetrical devices such as corkscrews , purses or can openers are normally designed for right-handers, but can also be purchased in mirrored form.
  • Cameras are usually designed to be released with the right hand, i.e. with the shutter release on the top right - easily accessible for the right index finger. Only the Japanese manufacturer Yashica brought a left-handed version of a camera model onto the market in 1989 with the Yashica Samurai ZL. In many cases, not only the right but also the left eye can be used if this should dominate.
  • Wristwatches are also mostly designed to be worn on the less stressed arm, for right-handed people the left. There are some manufacturers who make special left-handed watches in which the crown is attached to the left of the case, so that they can be operated much more easily with the left hand. The orientation of the watch strap clasp can be aligned accordingly.

Tools, machines

Some tools, for example grinding machines and drills , contain an increased risk of accidents for left-handers when they are conventionally equipped, since the handling according to the manufacturer's specifications does not correspond to their preferred mode of operation. The locking button is very often on the left side of the handle. As a result, a left-handed person now has it under the palm of his hand instead of his thumb and often unintentionally actuates it when gripping firmly.

In firearms, the one-sided safety lever is generally designed for the thumb of the right hand. With newer firearms, double-sided or centrally arranged (trigger or grip) safety devices are increasingly being used.

Musical instruments

Handed music making

When making music according to handicap, the tasks of the hands are distributed according to their particular strengths and enable optimal interaction. For right-handers with conventional instruments, this goes without saying. The consideration of handedness when making music is becoming increasingly important among music educators. Various instruments are already available in specific versions for left-handers, especially popular musical instruments such as guitars and electric basses . Mirror-inverted pianos or grand pianos are a real rarity . Consequently, suitable sheet music was developed.

A violin is not only chiral in terms of the covering, but also because of the asymmetrically arranged built-in components in the body: bass bar and sound post. The bow for painting is symmetrical except for the right-hand thread of the tensioning screw. Very simple recorders all have holes in the middle plane, better ones have a lower grip hole for the right little finger that is slightly offset to the right. If this finger hole is on a separately pluggable and rotatable flute section and if it is not asymmetrically resolved in 2 partial bores, this flute can also be played left-handed.

Almost all musical instruments are asymmetrical, especially keyboard, accordion and string instruments. So they cannot simply be played in mirror image. Therefore, left-handers have mostly learned these instruments in the same way as right-handers. There are left-handers who, in spite of this wrong way of playing, achieve great skill. According to the music teacher and cellist Walter Mengler , there can also be problems similar to those when retraining the writing hand:

  • Under-demanding of the dominant hand and excessive demands on the non-dominant hand
  • Disturbance of balance and coordination
  • Higher demands on brain performance due to additional coordination tasks
  • Faster fatigue through permanently higher effort
  • Limitation or inconsistency in musical expression
  • It is less easy to achieve a sense of wellbeing while playing (so-called ' flow ').

These problems can be prevented by playing instruments that are appropriate for handicap. However, there are (still) some factors that prevent this:

  • To date, professional orchestras have generally not accepted left-wing musicians.
  • Not every instrument is available in a left-handed design. Sometimes you have less choice, or there is a lack of appropriate loan instruments for beginners.
  • All valuable historical string instruments are only available in the right-handed version.
  • Many teachers refuse to teach left-handed instruments and have little experience with this style of playing.

So it must always be decided individually whether a left-handed or a conventional instrument is learned / played.

Instruments

  • String instruments , for example string and plucked instruments, usually belong to the slightly asymmetrically built instruments. Simply re-tensioning the strings is not enough for left-handed play. However, individual companies and manufacturers offer specially built instruments for left-handers. The conversion of an existing conventional instrument is also possible with some effort. A particular advantage of hand-based playing is that tone and expression are generated with the dominant hand. Attention: Guitars seem to be side-symmetrical except for the strings, but the bridge inlay is almost always used asymmetrically on western and electric guitars, so that mirror-inverted strings are not possible. However, violins are also built chirally inside for better sound production, a correct "left" violin must be built as such from the ground up.
  • Woodwind instruments can be played by left-handers as well as right-handers, despite their asymmetrical application, since both hands perform comparable activities and the sound is generated through the mouth. It is believed, however, that there are advantages when the dominant hand takes over the part of the grips further away from the body. Recorders are also available with holes for left-handers.
  • Brass instruments: The perfect left-handed instrument is the French horn , because the valves are operated with the left anyway, while the right hand is used to plug the bell. Valveless trombones can be immediately converted for left-handers by rotating the bell, all other brass instruments are built right-handed.
  • Percussion: Skin instruments are predominantly symmetrical. The drums are constructed, however, must be completely mirrored for left-handers; This is straightforward for most parts of the instrument, but there are, for example, double foot machines for quickly operating the bass drum for left-handers, as the left foot is usually the leading one when working on the drums. Percussion instruments with a distinct pitch ( vibraphone , xylophone , marimba , glockenspiel , etc.) are not symmetrical. They could easily be rotated 180 ° so that the high notes are on the left and the low notes on the right, but the pentatonic series is then in front and not in the back, as is the other way around.
  • Harp: The harp only appears symmetrical at first glance (in the sound box), but is inclined in the neck and lies on the right shoulder. However, left-handed harps are also built, with these the strings and keys (if available) being inverted. Since the harp is played with both hands, a left-handed harp is not necessary. It depends a lot more on the piece and which hand plays the melody. Playing the harp is good practice for using both hands.
  • Keyboard instruments such as the piano cannot be converted into left-handed instruments without completely redesigning them, since the high notes are on the right, the low notes on the left and the pentatonic row on top. Very few left-handed pianists, such as B. Christopher Seed or Géza Losó , play on a piano designed for left-handers. However, electronic instruments offer a much easier way to mirror the keyboard.

Sports

In elite sport, the proportion of left-handers is higher than in the general population. This is especially true for fighting and backlash sports such as boxing , tennis , table tennis , badminton and fencing . The proportion of left-handers among top athletes is between 20 and 55 percent, depending on the sport. In those sports in which competitors have to watch their opponents in order to plan their own reactions to the actions of the opponents, the proportion of left-handers among top athletes is particularly high. The main reason is that athletes normally have to deal with right-handed people much more often and are trained in their movements. However, many of these trained schemes fail in competition with left-handers. The better spatial processing in the dominant right hemisphere, which is often noticeable in left-handers, appears to be advantageous when assessing movement sequences.

The footprint, which is important in other sports such as soccer , long jump , high jump or figure skating , is directly related to left-handedness. When it comes to snowboarding, a distinction is made between the front foot when riding normally (left = regular, right = goofy).

Christian Zeitz, left-hander and handball world champion
  • Handball : In handball, left-handers have significant advantages over right-handers when attacking the right-wing and back-right playing positions . These result - especially in the right wing position - from the significantly more favorable throwing angle when the ball is thrown at the goal with the left instead of the right hand. In the lower game classes and in the youth sector, the "unusual" ball control with the left hand offers advantages in overcoming the defensive measures that are mostly only reflexively adapted and learned to right-handers. Many goalkeepers are also somewhat irritated by the “mirror-inverted” sequence of a left-handed thrower's throw. For these reasons, the game positions on the right-hand side in attack are occupied by left-handers in almost all teams.
  • Boxing : Left-handed people are usually southpaws in boxing . Left-wing extremists (“normal” boxers) find it particularly difficult to switch to the right-wing angle of their opponents against right-wing officers. In the United States, this legal display of the "wrong foot forward" is frowned upon. Young boxers are often "reeducated" to be left exposed. For southpaws there is the term Southpaw (literally: south paw ), taken from baseball . American boxers usually have considerable difficulties with the legal display. Left-handers are used to moving around their opponent to the right. With a southpaw, you have to circle clockwise around him to move away from his left flapping hand.
Timo Boll is left-handed
  • Table tennis , tennis and badminton : for a left-handed person, the right-handed opponent is the norm. Reflexes and movements are usually trained against a right-hander. The left-hander is therefore optimally prepared for such "normal" opponents. In contrast, a left-handed opponent is a special case for right-handers, for example fore and backhand are swapped. The usual rhythm during rallies does not come about. Left-handers are thus better trained for the games with right-handers than the other way around. If two left-handers play against each other, they also have problems adjusting to their opponent. But since both have these problems, it is not detrimental to either player.
  • Baseball : Left-handed batsmen are particularly dangerous in baseball, as they have advantages in terms of visibility and ball movement compared to right-handed batsmen with the mostly right-handed throwers. It is also considered a tactical advantage to have left-handed throwers in the squad in order to force left-handed batsmen into left-left duels and thus to be able to reverse the effect.
  • Sports shooting : For left-handers in shooting sports, most gun manufacturers have sports guns with exchangeable grips. Problems often arise from the fact that the club's own weapons are used to learn to shoot, most of which are only available in right-handers. In the shooting range / competition, the marksman (right-handed) usually looks at the back of his or her left (short gun) or right (long gun, sports bow) neighbor. The unfamiliar look into the face of the person standing next to you (left-handed) can lead to irritation for some shooters, whereas looking into the face of the person standing next to you is normal and therefore routine for left-handed people.
  • Bowling : Left-handers usually have the advantage in bowling that the left half of the lane is not played as often and so there is more oil there. However, players without their own ball have the disadvantage that the "house balls" of the bowling facilities are usually drilled for right-handers.
  • Polo : In polo, left-handers are generally at a disadvantage, as all players have to play the stick (polo stick ) with their right hand.
  • Golf : In golf, a little more strength is usually required with the left hand while the right hand guides the club. With left-handed bats, it's the other way around. There are minimal random differences in difficulty on the course. A kinked track ( dogleg ) compensates for the typical mistakes of one player, while the other's balls are all the worse for the same mistake.
  • Jai Alai : You can only play with the right hand. Here it is above all safety reasons that dictate this rule.
  • Judo : In Judo, every technique can be used the other way around, i.e. instead of grabbing the left side of the lapel (from the opponent) with the right hand, one grabs the left hand into the right side of the lapel (from the opponent) and grabs with the right hand in the sleeve. This surprises most opponents, but in most dōjōs the techniques are taught with both hands so that right-handed people can counter with left-handed. Even if the second technique with the right in the sleeve is called “left-handing”, it makes more sense for left-handers, whose stronger arm is usually the left, to use the greater force with the left in the sleeve, ie “right-handing” .

Research on left-handedness

Problems of left-handed research

With regard to targeting and subject selection, research on left-handedness has been and is fraught with some problems:

  • There is no uniform definition of left-handedness when selecting the test subjects. Sometimes only left-handers, and sometimes retrained people, count as left-handers, in other cases both-handed people are categorized or specific tests are carried out for classification.
  • The research provides statements that relate to very different groups of people, be it left-handed people in general, retrained left-handers or the specific subgroup of trauma-related left-handers. It is only in the last few decades that studies have increasingly delineated whether aspects of left-handedness per se or the consequences of retraining are discussed.
  • For a long time, left-handedness was treated as a medical deviation or deficit and researched purely from this point of view. Therefore, research into the causes and research into possible brain damage initially took up a large part of the focus. However, brain research was and is generally not carried out on healthy people, but on previously ill people. However, this group of patients cannot be regarded as meaningful for objective left-handed research.
  • For a long time, research into the localization of brain functions was based solely on the right-handed test person (although it was not taken into account that they always included re-educated left-handed people). Findings about left-handed people result from the reversal of the brain side dominance with a predefined distribution of tasks. There are, however, well-founded indications that the brain may have different structures in left-handed people (e.g. the language center is more often distributed over both hemispheres).

Root cause research

A possible cause of left-handedness is the lateralization of the brain , especially an innate right hemispheric dominance. The effects of dominance of the right hemisphere are not yet known or explored in full. The dominance of one hemisphere of the brain is most clearly expressed with the handedness, but there are also preferences for the legs ("feet"), the eyes and the ears.

Genetic causes of left-handedness are likely, however, in the research into the inheritance patterns you meet again to other findings: Among monozygotic twins combinations come from either hand like frequently as with other sibling pairs, though identical twins are genetically almost identical. A 1998 study by James McDevitt University in Oklahoma also showed that children whose parents are both left-handed are only 26 percent likely to become left-handed themselves.

The professional world is therefore divided, also because no gene has yet been found that can be attributed to handedness. Some scientists believe that there is no genetic cause for left-handedness. Others have developed theories that try to explain the low inheritance of left-handedness. Psychologist Chris McManus has developed a model based on two different alleles . After this there is a C and a D allele. The D allele promotes right-handedness, while the C allele affects handedness randomly. If a person has two D alleles, he becomes right-handed . With one or two C alleles, however, there is a certain likelihood of left-handedness. Similar mechanisms, called balanced polymorphism , are also known from other phenomena in nature (for example from sickle cell anemia ).

In August 2007, the discovery of a gene (LRRTM1) was published that is said to be responsible for left and right-handedness. However, this discovery contradicts the study at McDevitt University listed above, since identical twins are genetically the same.

Another hypothesis for the causes of left-handedness is the Geschwind-Behan-Gallura model , according to which sex hormones influence the lateralization of the brain during embryonic development. This view is held by some researchers, but like gene theory, it is controversial, among other things because it contradicts twin studies. The hormone hypothesis is used as a possible explanation for studies that have shown a significantly higher risk of left-handed people suffering from breast cancer and the autoimmune disease multiple sclerosis .

According to Rik Smits, however, such individual studies are initially not scientifically meaningful, as connections between two phenomena can be established relatively easily. In the past, numerous medical and psychological abnormalities or character deficiencies have been associated with left-handedness (from difficult to educate to alcoholism and crime). On closer inspection it later turned out that the studies yielded random hits, were fraught with errors or the research approach was not objective due to prejudices against left-handedness.

Conclusion: There have already been numerous attempts to research the cause of left-handedness. Nevertheless, none of the previous theories could clarify alone and without contradiction how a person's hand preference arises.

Others

Left handed day

Lefthandersday in London 2002

Dean R. Campbell , who also founded Lefthanders International in 1975 , proclaimed August 13th to be International Lefthanders Day, which has been celebrated since 1976.

The 13 in the date was chosen as a sign against superstition because left-handedness was often associated with corresponding ideas.

In recent years, Left-Handed Day has increasingly stimulated reports of left-handedness on August 13 in various media.

Legends about left-handed people

Errors in statistical analysis have given rise to numerous legends about left-handedness. However, statistically significant differences were also found.

In the literature, left-handers are sometimes ascribed special characteristics that, statistically speaking, should be more pronounced in them than in right-handers. It is mentioned, for example, that left-handers are on average more intelligent than right-handers. In popular scientific literature in particular, the dominance of a certain half of the brain associated with handedness is associated with statistically predominant strengths, weaknesses and personality traits. It is also assumed that left-handed people think and act creatively , while right-handed people tend to act rationally in the majority .

However, it must always be taken into account that, especially in the older generation, only some of the actual left-handers were recognized as such. Those who "professed" themselves to be left-handed could represent a certain selection that distorts the overall impression.

However, the conclusion that left-handed people have a shorter life expectancy because they are poorly adapted to the right-handed-dominated world and therefore have a higher risk of accidents has turned out to be incorrect. In fact, this statistical phenomenon is most likely due to the retraining to the right hand, which was particularly frequent in the past and which reduces the proportion of left-handers in older people.

A study by neurologist Norman Geschwind from 1982 found that left-handed people are more likely to have certain diseases, including allergies. This quickly established itself in public. However, numerous follow-up studies have shown that there is no such connection. The reason for this lay in Geschwind's methodology: He had asked customers in a left-handed shop and compared their answers with a random control group. Since the left-handers were informed about the purpose of the study and were also happy to provide information out of interest, the information provided was much more detailed than that of the right-handers, who had no personal reference to the subject of the study.

income

A study of the incomes of 5,000 Americans aged 28 to 35 found that male academics earned 15 percent more income for left-handers than right-handers. There was no significant difference between non-academics and women.

In another study with almost 2000 Britons aged 33 years, left-handed men had a 4% higher income than right-handed people and left-handed women had an income around 4% lower than right-handed women.

US presidents

Barack Obama signing

Four of the five Presidents of the United States from 1981 to 2017 were left-handed: Ronald Reagan (1981–1989), George Bush (Senior) (1989–1993), Bill Clinton (1993–2001) and Barack Obama (2009–2017). Before that, only Gerald Ford (1974–1977) and Herbert C. Hoover (1929–1933) were left-handed secured. James A. Garfield (1881, statement not confirmed) and Harry S. Truman (1945–1953) are considered to be two-handed, which usually speaks for retrained left-handed people. Ronald Reagan was also a retrained left-hander for writing.

There were three candidates running in the 1992 presidential election, and all three - George Bush Sr., Bill Clinton, and Ross Perot - were left-handed. The same picture was there in 1996: Clinton, Perot and Bob Dole were all left-handed, with Dole being a retrained right-handed. His right arm has been paralyzed since he was wounded in World War II. In the presidential elections in 2000, the left-hander Al Gore won the majority of the votes, but failed due to the electoral system to the right-hander George W. Bush . After two right-handers were in the running in 2004 with George W. Bush and John Kerry , both candidates were left-handed again in 2008: Barack Obama and John McCain . President Donald Trump, who has been in office since 2017, is right-handed, like his former competitor Hillary Clinton.

Movies

literature

Web links

Wiktionary: left-handed  - explanations of meanings, word origins, synonyms, translations
Commons : Left-handedness  - collection of images, videos, and audio files

Individual evidence

  1. ↑ G. Wirth: Speech disorders, speech disorders, childhood hearing disorders . 5th edition. Deutscher Ärzte-Verlag , Cologne 2000, ISBN 3-7691-1137-0 ( online [accessed on September 6, 2012]).
  2. ↑ Alfred Zuckrigl: Left-handed children in family and school . 5th edition, Reinhardt-Verlag, Munich 1995, ISBN 3-497-01370-6 .
  3. ^ Walter Mengler: Making music with the left . Schott, Mainz 2010, p. 12f.
  4. ↑ Sally P. Springer: Left - Right Brain. Functional asymmetries. 2nd edition, Spektrum, Heidelberg 1988, Chapter 5, ISBN 3-922508-14-6 .
  5. ↑ Carola Beck and Britta Pawlak . Typically left-handed - what are the differences?
  6. ↑ Arnd Krüger (2018). Left handed. Competitive sport 48 (5), 29.
  7. ↑ Left-handed test. Retrieved September 25, 2019 .
  8. ↑ Johanna Barbara Sattler: The retrained left-hander or the knot in the brain. Auer, Donauwörth 1995, ISBN 3-403-02645-0
  9. ^ Rolf W. Meyer: Left-handed? . 5th edition, Verlag Koch and Humboldt, Höfen 2001. ISBN 3-7081-9862-X . P. 62f.
  10. ↑ a b Rolf W. Meyer: Left-handed? . 5th edition, Verlag Koch and Humboldt, Höfen 2001. ISBN 3-7081-9862-X . P. 58.
  11. ↑ Sally P. Springer: Left - Right Brain. Functional asymmetries. 2nd edition, Spektrum, Heidelberg 1988. ISBN 3-922508-14-6 . P. 94f.
  12. ↑ [1] From: welt-der-linkshaender.de, Feb. 2019.
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  14. ^ Rationelle Stenografie Stiefografie: Links-Steno , accessed on April 1, 2016.
  15. ↑ Stepography especially for left-handers. In: stenografie-stiefografie.beepworld.de.
  16. ↑ For further literature see literature. In: First German advice and information center for left-handers and retrained left-handers.
  17. ^ Hinnerk Becker: Neuropsychiatric aspects of left-handedness. In: Udo Schneider (Ed.): Aspects of the psychic. Festschrift on the occasion of the 60th birthday of Hinderk M. Emrich. Königshausen and Neumann, Würzburg 2004, ISBN 3-8260-2729-9 , p. 20.
  18. ↑ Dr. Johanna Barbara Sattler: Psychological problems through retraining In: Psychologie heute No. 10/1985
  19. ↑ Stefan Klöppel u. a .: Can Left-Handedness be Switched? Insights from an early switch of handwriting. In: Journal of Neuroscience. 27, No. 29, 2007, pp. 7847-7853, doi : 10.1523 / JNEUROSCI.1299-07.2007 .
  20. ↑ Left-handed people never become real right-handed people. In: sueddeutsche.de. October 11, 2007 (on the study in Journal of Neuroscience).
  21. ^ Sylvia Weber: Supporting left-handed children properly 4th edition, Reinhardt Verlag, Munich 2014. ISBN 978-3-497-02479-7 . Pp. 51-55.
  22. ↑ Is there really no left-handed camera currently on the market ?, Any questions? Wissenscommunity , stern.de, August 25, 2012. Accessed March 2, 2015.
  23. ↑ Yashica Samurai Z / ZL / Z2 , camera-wiki.org. Retrieved March 3, 2015.
  24. ↑ http://www.linkshaender-beratung-muenster.de/LinkshaendigkeitMusik.html
  25. ↑ - ( Memento of the original from July 14, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.gezaloso.de
  26. ↑ http://www.gezaloso.de/index.php/linkshaender-notation.html
  27. ↑ First piano for left-handers. Left Hand Corner, April 7, 1999, accessed July 7, 2013 .
  28. ↑ The secret of successful left-handers. In: Welt Online. July 18, 2007.
  29. ↑ Sports. In: linkshaender-beratung.de. Retrieved September 4, 2007.
  30. ↑ Hartmut Scherzer: Southerner - Really just boring? In: Sport-Bild. March 22, 1995, p. 48.
  31. ↑ Harry Valérien: On the "pleasure" of being a leftist. About experience as a right and left hander. In: Frankfurter Allgemeine Zeitung. April 5, 1993, p. B7.
  32. ↑ Regulations. In: German Polo Association. Retrieved July 18, 2010.
  33. ↑ Rik Smits: Everything with the left hand. Rowohlt, Berlin 1994, ISBN 3-87134-096-0 , p. 163.
  34. ↑ Rik Smits: Everything with the left hand. Rowohlt, Berlin 1994, ISBN 3-87134-096-0 , pp. 142-149.
  35. ↑ Werner Stangl: Right versus left brain hemisphere? In: Werner Stangl's worksheets. Retrieved June 7, 2010.
  36. ↑ Right or left: Not just with your hands. In: Medizinauskunft.de. August 12, 2004, accessed September 10, 2007.
  37. ↑ Tinka Wolf: Researchers discover left-handed gene. In: Welt Online. August 2, 2007, accessed September 4, 2007.
  38. ↑ MK Ramadhani, SG Elias, PA van Noord, DE Grobbee, PH Peeters, CS Uiterwaal: Innate left handedness and risk of breast cancer: case-cohort study. In: BMJ (Clinical research ed.). Volume 331, number 7521, October 2005, pp. 882-883, doi : 10.1136 / bmj.38572.440359.AE , PMID 16186135 , PMC 1255796 (free full text).
  39. ↑ a b L. Titus-Ernstoff et al .: Left-handedness in relation to breast cancer risk in postmenopausal women. In: Epidemiology. 11, 2000, pp. 181-184. PMID 11021617 .
  40. ↑ L. Fritschi, M. Divitini, A. Talbot-Smith, M. Knuiman: Left-handedness and risk of breast cancer. In: British Journal of Cancer . Volume 97, Number 5, September 2007, pp. 686-687, doi : 10.1038 / sj.bjc.6603920 , PMID 17687338 , PMC 2360366 (free full text).
  41. ↑ Increased risk in left-handed women. In: Spiegel Online. September 26, 2005.
  42. ↑ More breast cancer in left-handed women. In: scinexx. September 26, 2005.
  43. ↑ H. Gardener, K. Munger, T. Chitnis, D. Spiegelman, A. Ascherio: The relationship between handedness and risk of multiple sclerosis. In: Multiple sclerosis. Volume 15, number 5, May 2009, pp. 587-592, doi : 10.1177 / 1352458509102622 , PMID 19389750 , PMC 2771381 (free full text).
  44. ↑ Rik Smits: Everything with the left hand. Rowohlt, Berlin 1994, ISBN 3-87134-096-0 , pp. 161-165.
  45. ↑ Official website of International Lefthanders Day , accessed April 1, 2016 (English)
  46. ↑ a b Article about the International Left-Handed Day in the newspaper 'Die Welt', accessed on August 13, 2016.
  47. ^ Norman Geschwind, Peter Behan: Left-handedness: Association with immune disease, migraine, and developmental learning disorder. (PDF; 898 kB) In: Proceedings of the National Academy of Sciences . 79, No. 16, 1982, pp. 5097-5100, PMID 6956919 .
  48. ↑ Christopher S. Ruebeck, Joseph E. Harrington & Robert Moffitt: Handedness and earnings. In: Laterality: Asymmetries of Body, Brain and Cognition, Vol. 12, No. 2 (2007). Pp. 101-120.
  49. ↑ Kevin Denny & Vincent O'Sullivan: The Economic Consequences of Being Left-Handed: Some Sinister Results. In: The Journal of Human Resources, Vol. 42, No. 2 (2007), pp. 353-374.
  50. ↑ "Left-handed". A 45-minute film on arte. In: lefthandcorner.wtal.de. December 5, 2003.