handedness


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handedness,

habitual or more skillful use of one hand as opposed to the other. Approximately 90% of humans are thought to be right-handed. It was traditionally argued that there is a slight tendency toward asymmetrical physiological development favoring the right side of the body, and that the center of gravity is to the right of the body's midline. This, however, would seem to be the consequence of greater dependence upon the right hand rather than the cause of right-handedness.

The neurological argument holds that since the right and left sides of the body are controlled by the opposite hemispheres of the brain, the greater development of the left hemisphere results in right-handedness. Anatomical studies have demonstrated that Broca's center, the area of the cerebral cortex that controls speech and muscular coordination, is almost always better developed in the left hemisphere in right-handed individuals; in 70% of left-handed individuals these centers are located in the right brain. Psychologists have raised the possibility of a cultural explanation. Although young children can be trained to prefer the right hand against a natural inclination, there is evidence that handedness is hereditary and that denser neurological connections extending from one side of the brain or the other are present from birth. A cultural explanation is also challenged by the evidence that some other vertebrates demonstrate a preference for one hand or paw over the other.

Although it is not clear that culture is a causative agent in handedness, it is certain that the high incidence of right-handedness has shaped human society in almost every conceivable aspect. Tools, machinery, and even clothing are largely designed for the right-handed, and until fairly recently, many left-handed individuals were strongly encouraged to switch to right-handedness. In some cultures the left-handed were thought to be evil or to bring bad luck.

handedness

[′han·dəd·nəs]
(physics)
A division of objects, such as coordinate systems, screws, and circularly polarized light beams, into two classes (right and left), which distinguishes an object from a mirror image but not from a rotated object.
References in periodicals archive ?
Almost all left-handed people experienced problems in everyday lives related to work and relations purely because of their left- handedness. Sometimes people around them appeared to turn their back on them.
Handedness as a function of twinning, age and sex, Cortex, 30 (1): 105-111.
Handedness has been assumed to have some relationship with the creativity (Stewart and Clayson, 1980) as left handers tend to be higher on intellectual (Ghayas and Adil, 2007) and creative abilities.
When the entire room is standardized, including handedness, it is reasonable to say that standardization and same-handedness are essentially the same.
Findings from handedness research indicated that left-handed individuals (relative to right-handed individuals) had more divergent thought processes (Coren, 1995) and were more emotionally expressive (Jackson, 2005).
Handedness, footedness, eyedness and eardness are the peripheral indicators of hemispheric lateralization.
Two to 30% of any human population is left-handed or ambidextrous, with most estimates hovering around 10%, depending upon the criteria used to assess handedness." Interesting facts and odd lefty superstitions: Left-handers adjust more readily to seeing underwater
Handedness was determined in the study by asking the person whether or not they considered themselves right handed or left handed and by observing the dominant hand used when writing and engaged in other tasks involving pencil use.
What are lefties' perceptions of their handedness and their thoughts on the accommodations they need to make in school?
The term 'ambiguous' handedness was suggested for changes of hand between trials of the same task (Soper & Satz, 1984).
Explaining the medical aspect of handedness, Dr Jaju points out that the brain is divided into two hemispheres, one of which is always dominant and which controls motor skills.
"We think breastfeeding optimises the process the brain undergoes when solidifying handedness," said Philippe Hujoel, the study's author.