Left-handedness is the preference for the left hand over the right for everyday activities such as writing. Being left-handed can be advantageous in some sports and games, although sometimes special equipment is required. Some everyday items such as scissors and other tools also have left-handed variants.

In 1998, a study suggested that approximately 7 to 10 percent of the adult population was left-handed. Studies indicate that left-handedness is more common in males than females. Left-handedness, in comparison to the general population, also appears to occur more frequently in both identical and fraternal twins. Statistically, the identical twin of a left-handed person has a 76 percent chance of being left-handed, identifying the cause(s) as partly genetic and partly environmental.

Accessibility of implements and skills
Left-handed people are sometimes placed at a disadvantage by the prevalence of right handed tools in society. Many tools and devices are designed to be comfortably used with the right hand. For example, (right-handed) scissors, a very common tool, are arranged so that the line being cut along can be seen by a right-handed user, but is obscured to a left-handed user. Furthermore, the handles are often molded in a way that is difficult for a left-hander to hold, and extensive use in such cases can lead to varying levels of discomfort. Most importantly, the scissoring or shearing action - how the blades work together (how they are attached at the pivot) - operates correctly for a right-hander, but a left-hander will tend to force the blades apart rather than shearing the target substance.

The lack of left-handed tools and machines in many workplaces is not only a nuisance to many left-handers, but has actually placed them at peril. One example is the band saw, whose standard design is convenient for right-handers but encourages left-handers to pass their arms dangerously close to the cutting blade with every pass of the saw. In fact, some factories have installed left-handed equipment after successful class-action lawsuits on behalf of left-handed employees.

Left-handed adaptations have even bridged the world of music, guitars are often made especially for lefties, and there have even been inverted pianos where the deepest notes correspond to the rightmost keys instead of the leftmost. Inverted trumpets are made, too, but at a considerably higher cost. The prevailing belief is that left-handed trumpeters aren't at a significant disadvantage; the French Horn, for example, is played with the left hand, yet most horn players are right-handed.

Left-handed golf clubs were one of the earlier, and well-accepted, manifestations of a special version of an implement; the most notable left-handed-playing participant being Phil Mickelson (he is naturally right-handed).

Left-handedness and intelligence
In his book Right-Hand, Left-Hand, Chris McManus of University College London, argues that the proportion of left-handers is rising and left-handed people as a group have historically produced an above-average quota of high achievers. He says that left-handers' brains are structured differently in a way that widens their range of abilities, and the genes that determine left-handedness also govern development of the language centers of the brain.

McManus also says that the increase in the 20th century of people identifying as left-handed could produce a corresponding intellectual advance and a leap in the number of mathematical, sporting, or artistic geniuses.

In 2006, researchers at Lafayette College and Johns Hopkins University in a study found that left-handed men are 15 percent richer than right-handed men for those who attended college, and 26 percent richer if they graduated.

Possible effects in humans on thinking

There are many theories on how being left-handed affects the way a person thinks. One theory divides left- and right-handed thinkers into two camps: visual simultaneous vs. linear sequential.

According to this theory, right-handed people are thought to process information using a "linear sequential" method in which one thread must complete its processing before the next thread can be started.

Left-handed persons are thought to process information using a "visual simultaneous" method in which several threads can be processed simultaneously. Another way to view this is such: Suppose there were one thousand pieces of popcorn and one of them was colored blue. Right-handed people-using the linear sequential processing style-would look at the popcorn one at a time until they encountered the blue one. The left-handed person would spread out the pieces of popcorn and look at all of them to find the one that was blue. A side effect of these differing styles of processing is that right-handers need to complete one task before they can start the next. Left-handers, by contrast, are capable and comfortable switching between tasks. This seems to suggest that left-handed people have an excellent ability to multi-task, and anecdotal evidence suggests that there are more creative stems due to this ability to multi-task.

Right-handed people process information using "analysis", which is the method of solving a problem by breaking it down to its pieces and analyzing the pieces one at a time. By contrast, left-handed people process information using "synthesis", which is the method of solving a problem by looking at the whole and trying to use pattern-matching to solve the problem.

The hypothesis that left-handed people are predisposed to visual-based thought has been validated by a variety of evidence. In the 2004 book Brains That Work a Little Bit Differently, researchers Allen D. Bragdon and David Gamon, Ph.D., briefly described some of the current research on handedness and its significance. "Handedness researchers Coren and Clare Porac have shown that left-handed university students are more likely to major in visually-based, as opposed to language-based subjects. Another sample of 103 art students found an astounding 47 percent were left- or mixed-handed."

Ultimately, being left-handed is not an all-or-nothing situation. The processing styles operate on a continuum where some people are more visual-simultaneous and others are more linear-sequential.

Get here Famous Left-Handers by clicking on the button "Hall of Fame", and dont forget to browse our selection of left-handers products "