Aug 132013

International Left Handers’ Day is held annually every August 13th. It was founded by the Left-Handers’ Club in 1992, with the club itself having been founded in 1990. 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. . . . 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!”


Handedness is a vague term that does not have a fixed or agreed upon definition. Although the terms left and right are enough to define handedness in an ordinary sense, they do not suffice for scientific research. Handedness can be defined two ways scientifically. It can be defined as the hand that performs faster or more precisely on tasks, or the hand that a person prefers to use, regardless of performance. In a scientific study, it should be recognized that handedness is not a discrete variable (right or left), but a continuous one that can be expressed at various levels between strong left and strong right. There are four basic types of handedness: left handedness, right handedness, mixed handedness, and ambidexterity. Globally, roughly 12% of men and 10% of women are left-handed using the definition of the hand that is more adept at tasks.

People who are strongly right or left handed are in the vast majority worldwide. Mixed handedness refers to those people who prefer different hands for different tasks.  True ambidexterity, the lack of preference for right or left, is exceptionally rare.  Below is the remarkable Chen Siyuan, 24. She can write different things simultaneously with her right and left hands, which includes writing vertically with one and horizontally with the other, as well as writing in Chinese with one hand and in English with the other. She learnt to do this in order to cope with masses of homework in high school!


With a moment’s thought the complexity of the nature of handedness is apparent. For example, a strongly right handed person who learns to play violin (or most other stringed instruments) must develop fine motor skills and co-ordination with the left hand that often surpass the right.  Piano players, to be successful, must have balanced skills with the right and left hand.  A predominantly right or left handed baseball player can learn to bat from the opposite side to become a switch hitter. Thus there is both a genetic and a learned component in handedness.  The genetic component is represented by a single gene. All strongly right- or left-handed people can become more adept with the opposite hand with practice. People with injuries to the dominant hand perforce learn to use the opposite hand, and can attain considerable skill.


Human cultures are predominantly right handed, and so the right-sided trend may be socially as well as biologically enforced. This is quite apparent from a quick survey of languages. The English word “left” comes from the Old English (Anglo-Saxon) word “lyft” which means “weak” or “useless.” Similarly, the French word for left, “gauche,” is used to mean “awkward” or “tactless,” and “sinister,” means “left” in Latin.  On the other hand (!), in many cultures the word for “right” also means “correct”. The English word “right” comes from the Old English word “riht” which also means “straight” or “correct. “Dexter” is the Latin word for “right” giving us the English “dexterous.”

Scientists generally agree that based on standardized testing, such as IQ tests, there is no statistically significant difference between right and left-handers. But it seems likely that the brains of many left handers develop differently from those of right handers. This phenomenon is due to the fact that the human brain is asymmetrical, with the left and right hemispheres controlling different functions.  For example, the left hemisphere in most people controls the right side of the body and also language. Thus, writing with the right hand involves co-ordination within the right hemisphere, whereas writing with the left hand involves co-ordination between the right and left hemispheres.  Incidentally the notion that the left brain is logical and the right brain is creative is a popular misconc