China Library Classification Number R242 Document Identification Number B1672-5085 (2011) 35-0315-03.
In daily life, a person is used to calling himself left-handed with his left hand. The emergence of left-handed people has aroused the infinite exploration of scientific researchers. This paper explains the standard of handedness in detail, summarizes the proportion, advantages and disadvantages of left-handed, and discusses the theory of left-handed formation and its relationship with brain advantage from two aspects of physiology and psychology. Help readers to understand left-handedness and its research progress more comprehensively.
Keywords left-handed? Physiological psychology? research progress
Typical left-handed figures in history: Confucius in China, Napoleon in France, Hitler in Germany, Einstein with superior intelligence, Henry Ford and Benjamin Franklin; Leonardo da Vinci, Raphael, Beethoven, Michelangelo and Picasso; Gan Gan, Navratilova, Cai Zhenhua, etc. It can be seen that they are no more stupid than right-handed people. Of course, we can't say that left-handed people are smarter than right-handed people. We should treat right-handed people first and put an end to any discrimination.
Observe the people around you. Which hand do they use to do the following ten actions: holding a pen, chopsticks, throwing things, brushing their teeth with a toothbrush, holding scissors, striking matches, threading a needle, holding a hammer, holding a racket and washing their faces with a towel. The hand that a person is used to doing technical activities in daily life is the dominant hand. According to198911/China people's handedness classification standard formulated by the annual meeting of national medical psychology in June, if the above 10 people are accustomed to using their right or left hands, they are called strong right-handed or strong left-handed; If the first six movements are all right-handed or left-handed, and the 1 or 4 of the last four movements is with the other hand, it is called right-handed or left-handed; If you use the other hand in the first 6 steps 1 step and use the other hand in the last 4 steps, it is called mixed profit. If you write or hold chopsticks with your right hand and everything else is operated with your left hand, you are called a potential left-hander. [ 1]
1? The proportion of left-handed people
The scientific research on handedness is only 100 years old. According to a survey conducted by G. Broed in 1946, the leftists account for 2-6% of the total population. 1964 R. Brain thinks that the left-handers of Anglo-Saxons in England are 5 ~ 10%. In 1980s, China investigated 19 units in 4 provinces. A survey of 18593 normal men and women showed that 9 1.5 1% were right-handed, 8.26% were mixed-race, and only 0.23% were left-handed. [1, 3] Even if the potential left-handers are included, the left-handers in China account for only 1.84%, which is still lower than the average minimum left-handers in western countries.
2? Theory of handedness formation
2. 1 congenital genetic factors
The formation of handedness depends largely on heredity.
Psychologist Peter Hepper's research found that according to the ultrasound images of the fetus, handedness was formed before birth. This shows that handedness is not learned. [4]
C.Reif's research found that only 0.23 ~ 2. 1% of children whose parents are left-handed are left-handed, and the interest rate of left-handed children is raised to 17.3%, and the interest rate of left-handed children is as high as 46 ~ 50%. China's research also came to a similar conclusion. [5]
2.2 acquired influence
In C. Reif's research, among 56 children aged 4-7 who have developed left-handed interests, 48% have completely changed their right hands, 65,438+04% are still ineffective, and the remaining 38% sometimes use their left and right hands. Annett( 1989) expressed the right-handed gene as rs+ (that is, the right-handed gene). Its research shows that on the basis of congenital inheritance, acquired experience plays a leading role, and about 50% people may become left-handed. [3]
3? Relationship between handedness and brain superiority
3. 1 the development of handedness
It can be seen from the development of children that the movement of hands develops with the development of brain function, and the use of hands gradually leans to one side with the lateralization of brain function.
Babies before 7 months have no dominance tendency, and infants under 1 are almost equally likely to grasp things with their left and right hands. The right hand rate of baby girls is slightly higher than that of baby boys. [1] With the increase of age, the right-handedness rate gradually increased, from 2 to 3 years old to 79.2%, and then slowly increased to 85. 1% at the age of 7. [6] The rate of left-handed people decreases with age, and the rate of decline of boys is faster than that of girls. Before the age of 7, children were still swinging between left and right interests.
3.2 handedness and language superiority hemisphere
The cerebral hemisphere is responsible for the perception and movement of the contralateral body, so people whose right hemisphere is the dominant hemisphere are generally left-handed, and those whose left hemisphere is the dominant hemisphere are generally right-handed. Dexterity is regarded as the external reflection of the hemisphere of language function superiority. It is worth noting that handedness is a description of motor function, so there is no absolute and complete correspondence between dominant hemisphere and handedness.
In the study, it is found that13 of aphasia in left-handed patients is caused by right brain lesions, and 2/3 is still caused by left brain injury. 95 ~ 98% aphasia of right-handed patients is caused by left brain injury. This not only shows that both hemispheric injuries may cause aphasia, but also shows that the speech advantages of left-handed and right-handed people are mainly in the left hemisphere (figure 1).
Figure 1 the proportion of people who use left and right brains for language processing in the total population and different types of handedness.
(This figure is quoted from the reference: [4])
4? Advantages and disadvantages of left-handed people and related research progress
Although left-handed people have to endure elbows at dinner, tables suitable for right-handed people and scissors that are difficult to use, the advantages and disadvantages of left-handed people are roughly the same.
4. 1 Advantages of left-handed players
Left-handed people have many obvious advantages. Some scholars have found that the brain transmits information to the left side of the body through the central nervous system faster than to the right side of the body 15‰ second. Therefore, it is inferred that left-handed people have stronger image thinking and spatial cognitive ability than ordinary people. In addition, the right hemisphere of human beings focuses on emotion, intuition and art, and its function in representation and visual ability is stronger than that of the left hemisphere, which may be the reason why many famous architects, artists and chess players are left-handed.
Mathematical ability may also benefit from the full use of the right brain. Many excellent students in math study are left-handed or have good hands. The advantage of left-handed people can even be shown in basic arithmetic skills. [4]
Unilateral brain function reflects the specialization of hemispheric ability. A remarkable feature of left-handed people is that the lateralization of the brain is lower than that of right-handed people. The two hemispheres of the right-handed brain are very different in size and shape, while the two hemispheres of the left-handed brain are more similar. In addition, the left-handed people's bodies are more balanced on both sides, and the visual advantage of one side is not so obvious, even the fingerprints of their hands and the size of their feet are more symmetrical. [4] Left-handed people not only use their left hand, but also frequently use their right hand, which makes the left and right hemispheres of the brain develop relatively evenly. So generally speaking, the brain function of left-handed people is slightly better than that of ordinary people. [8] For example, left-handed people have stronger repair function after brain injury; People who are left-handed or use both hands have better pitch memory than most right-handed people. .
In addition to the advantages mentioned above, left-handed players also have an important feature, that is, sports advantage. Different events require different competitive ability factors, and different categories of events in the same event group are also different. The participation of athletes' special sports quality in activities is one of the important conditions to gain advantages in special events. According to the survey, in some sports, athletes with excellent performance are more from a certain type of handedness (chart 1). [4] The right hemisphere's schema and integrated information processing ability show the advantages of simple and direct decision-making in complex situations, which makes its sports advantage corresponding to the left focus on the rapidly changing confrontation skills. It can be seen that left-handed athletes may be more in line with this kind of events in terms of competitive ability structure, so they have sports advantages in these events. [7]
Chart 1? The handedness tendency of elite athletes in different sports
(This figure is quoted from the reference: [4])
4.2 Shortcomings of Left-handers
Left-handers are obviously related to anxiety neurosis, schizophrenia and other mental diseases. [2,9] China's 198 1 year survey figures also illustrate this point: in 1252 patients with schizophrenia, left rest is more than three times to ten times that of normal people. [10] Antipsychotics, antihistamines and sedatives can easily cause EEG changes.
They are not as fast, accurate and flexible as their right-handers. The habit of using hands is also related to sexual orientation, although this connection is sometimes weak and sometimes obvious. A meta-analysis of the two studies found that gay men and lesbians are 39% more likely to be left-handed than heterosexuals. However, we still notice that most homosexuals are right-handed. [2] In addition, left-handed people are more prone to dyslexia and suicidal tendencies. In the school environment, learning, especially writing, is more difficult for left-handed people than right-handed people except Arabic, and left-handed writing is in a forced backward posture than right-handed writing, thus promoting the development of abnormal posture of spine. [ 1 1]
Left-handers have known health risks. They may suffer from labor stress, such as premature delivery or need assisted breathing. They have to endure more headaches, more accidents (due to some right-handed devices), more knee and joint problems, more smoking and drinking, and more immune system problems (including allergic symptoms such as asthma, eczema and hay fever). [12] Some scholars have done research on this. In the survey of 189 college students, it was found that the incidence of left-handers was always higher than that of right-handers, among which 85% were involved in driving accidents. [ 13]
5? Research progress of left-handed people
With the development of physiological psychology and the intervention of cognitive psychology to explore brain information processing and types of physiological technology, we have seen a glimmer of light in revealing the mystery of the essence of left-handed sports advantage.
Many new research results are closely combined with the needs of society, such as the study that "women and left-handed people are prone to phobia", which has aroused social repercussions. The in-depth study on the lateralization of motor function as a skillful hand will further clarify the mechanism of asymmetry of higher psychological function in the cerebral hemisphere.
In Ankara, researchers from the Department of Physiology of Baskent University School of Medicine used the methods of oldfield and mcmanus to study the relationship between dominant eyes and left/right handedness of college students, and found that college students are mainly right-handed. Left/right handedness and dominant eyes seem to be the most reliable methods to study brain functional asymmetry and brain lateralization. [14] In the study of brain dominance in cerebral hemisphere, the computer measurement of X-ray photos of skull shows that 64% of right-handed people have wider temporal occipital region, while 46% of left-handed people have wider temporal occipital region, which shows higher opposite brain symmetry among left-handed people. [ 15]
Psychologist Stanley Collen stumbled upon an amazing fact: with the increase of age, the proportion of left-handed people decreased greatly, and other researchers around the world also confirmed Collen's discovery. [12] So Collen and halpern boldly thought of an incredible explanation: lefties died earlier. Since then, a lot of textual research and follow-up research have been carried out. According to some authoritative research results, there is no significant difference in life span between left-handed and right-handed people. [8] There are many people who live long in Zuo Li's hands, such as Benjamin Franklin (84 years old), Charlie Chaplin (88 years old), Pablo Picasso (92 years old), Empress Dowager Cixi (the mother of the current king of England) (105 years old) [12] and so on.
And some morbid lefties. In order to describe the concept of pathological left-handedness, the researchers analyzed various factors related to left-handedness in a large sample of adult paralysis attacks. The results show that there are three pathological factors related to left handedness: early onset of right hemiplegia, cognitive impairment and familial left handedness of patients with left hemisphere encephalopathy confirmed by clinical examination, but not the above pathological factors. The results support that there are significant differences between pathological left-handedness and normal left-handedness, which is of great significance for evaluating many abnormal situations that are assumed to be related to left-handedness at present.
The specific relationship between fixed humpback whales and left-handed people has attracted attention. The relationship between them has obvious biological significance, but the theoretical basis is still thin. Therefore, the conclusion that left handedness is a risk factor for fixed hunchback still needs further study and confirmation.
In 2007, researchers at Oxford University located the first gene LRR-Ml associated with left-handedness. Although people still don't understand the root cause of being left-handed, it is at least an improvement.
Take the exam and contribute.
[1] Huang Jianmin, Chen Weizhong, interesting talk about human body and health care secrets [A]. Southeast University Press, 1998, 1 1, (1): 73.
[2] (America) Spencer Rothers, Lisa valentino. Introduction to Contemporary Psychology, 7th Edition [a]. Shaanxi Normal University Press, 2006, 2:85.
[3] Liu Yu, the neural basis of language [A]. China Social Sciences Press 2007.12:12 ~113.
[4] (America) translated by Dennis Kuhn and Zheng Gang. Introduction to psychology: the way to understand thoughts and behaviors. (9th edition) [A]. China Light Industry Press, March 2004 (1): 92-93.
[5] China Encyclopedia Editor-in-Chief Psychology Editorial Committee of China Encyclopedia Publishing House. China encyclopedia of psychology [M]. China Encyclopedia Publishing House, 199 1 09, 1: 188.
[6] Chen Yunying .2004 Report on the Education Rights of Special Children in China [R]. People's Publishing House, 2005,03, 1.229.
Xie Hongguang, Sharla Cheung. Discussion on the phenomenon of left-handed advantage [J]. Journal of Guangzhou Institute of Physical Education, 2000,12,20 (4).
[8] edited by Yao Dehong and Kong. 100,000 New Sciences Why Human Body and Medicine Volume [J]. Zhejiang Science and Technology Press, 2000,0 (1): 30.
Zhang Yalin. Advanced psychiatry [M]. Central South University Press, 2007, 1: 442-443.
[10] Li Xintian. Distribution of left-handed and right-handed people in China [J]. Journal of Psychology, 1983(3).
[1 1] Left-handedness of pre-adolescent students and the risk of fixed hunchback. Translation: Lian Yufeng, Mononi Sim, Marku Heliovara, Yorma Seitsamo and Miko Pusa [J]. School Hygiene in China1998,4, 19 (2): 6544.
Miles (USA). Psychology [A]. People's Posts and Telecommunications Press, 2006, 10:76.
[13] Longshan. Don't force children to be left-handed [J]. Only child, 2002 (7).
[14] Nimit (u) Negundo (g) An. The relationship between eye advantage and handedness of college students under two different methods [J]. International Journal of Ophthalmology, 2009,9 (12).
[15] (America)? Moncastle, translated by Han Jisheng. Medical physiology [M]. Beijing: Science Press, 1988.605.