Left-handedness is the predominance of the development and function of the left hand over the right, usually inborn. Left-handedness can be hidden when a left-hander has learned to use mostly his right hand. In an emergency, requiring a quick and subconscious (reflex) action, hidden left-handedness may manifest itself in an attempt to perform this action with his left hand. And this when handling devices, instruments, etc., designed for right-handers, sometimes threatens (parachutists, pilots, chauffeurs, etc.). Hidden left-handedness can be detected by some signs: the left hand is larger and the nails are wider; when interlacing the fingers of both hands, the first finger of the left and not the right hand is placed on top. The leading eye in left-handedness is the left one, which, when serving in the army, does not allow marks from firing from the right shoulder . Children with left-handedness sometimes begin to speak a little later than they should, otherwise they develop normally both mentally and physically. Forced, with reproaches and ridicule, “retraining” a left-handed child often leads to his nervousness, stuttering, etc. But many left-handers get used to writing with their right hand without much difficulty.
Left-handedness is also acquired (for example, after a crippling injury of the right hand); The victim may need tools specially adapted "under his left hand" to preserve his former profession.Go
Left-handedness can be congenital (sometimes hereditary) and forced due to dysfunction of the right hand. There are explicit and hidden left-handedness; with the latter, the person, being born from a left-handed person, by training is trained to use mainly his right hand. Left-handedness, as well as right-handedness and the same development of both hands (ambidexteria), depends on different environmental conditions of origin and human development. In our environmental conditions, left-handed people make up 3% of the total population.
Of the 100 children aged 7-8 months. (time of manifestation of a grasping reflex) in three of them left-handedness is noted. The percentage of left-handers in other parts of our planet varies to a large extent (for example, it reaches 26% for Australians, and even more for South Africans). The asymmetry of the structure on the globe applies not only to humans, but also to all living beings, as well as plants - crowns, root systems and annual rings, well distinguishable in the transverse saw-cut of tree trunks.
Hidden left-handedness can be determined by the larger size of the left hand in a left-handed person, the greater development of the veins on the back of the left hand, the larger transverse size of the nails, the more developed mimic muscles on the left, and the movement of the hands during work.
When you squeeze the hands with interlaced fingers, the thumb of the left hand is on top; when applauding, a more active left hand is placed on top. When walking in a straight line with a blindfold, left-handers immediately deviate from a straight line from left to right, and right-handedly vice versa.
The prevailing development of the left half of organisms is also associated with a change in the direction of movement of living beings. Left-handedness, right-handedness and ambidexteria are regarded by some authors as hereditary traits. Left-handedness can be one of the twins. In countries where there is a large percentage of left-handed people, they write alternately with right and left hands in schools (Australia, etc.).Go
Among left-handed people, there are often people who write in the mirror direction from right to left - with their left hand, and from left to right - with their right, and sometimes they write lines vertically.
Left-handed people have two centers of speech - one in the left and the other in the right hemisphere, with hemorrhages in one of them comes a faster compensation for the development of speech. Left-handers, as a rule, have a left leading eye and left leading ear, unlike right-handed ones. They hit the target badly when shooting, if they aim from the right eye, and they shoot well if they aim from the left eye. Re-education by labor, physical education develops the parties to any limit, but the left side is still the prevailing side of left-handers. When raising, one should not oppress the child by the violent regime of re-education from left-handed to right-handed. Even without such upbringing, the child perfectly adapts to the environment, labor, and the mechanisms of production tools. This is taken into account in the schools of those countries where the percentage of left-handers is relatively high.
In a number of countries (England, Japan, China) they produce tools for the production and for left-handers.
Forced upbringing and accusations against a left-handed child can sometimes cause him mental changes, nervousness, disruption of the rhythm of life, speech, and stuttering. Unclear speech with an obscure pronunciation of the letter “p” is more common in left-handed people, as is color blindness, strabismus, and genoin epilepsy. Left-handed children often begin to speak at a later date, but in development do not lag behind right-handed.
Practice shows that a left-handed person, accustomed to perform any kind of responsible manipulation with his right hand, in a critical situation may suddenly manifest the predominance of the left. This is especially true for defensive actions, since the unconditioned reflex causes the hidden left-hander to act with his left hand. This must be taken into account, especially when selecting skydivers; it is necessary to accurately establish the reliability of the left-handed acquired reflex when pulling out a parachute ring, the location of which is designed to use the right hand. When piloting an aircraft, driving a car, when working on control panels designed for right-handers, in cases when quick resourcefulness and orientation is required, left-handed people can also make mistakes without sufficiently fixed training of the right hand.