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  3. Left-handers have been the subject of curiosity, stigma and even fear over the centuries. Researchers now, however, are recogniz

Left-handers have been the subject of curiosity, stigma and even fear over the centuries. Researchers now, however, are recogniz

admin2014-09-30  43
问题     Left-handers have been the subject of curiosity, stigma and even fear over the centuries. Researchers now, however, are recognizing the scientific importance of understanding why people use one hand or the other to write, eat or toss a ball.
    Handedness, as the dominance of one hand over the other is called, provides a window into the way our brains are wired, experts say. And it may help shed light on disorders related to brain development, like dyslexia(诵读困难症), schizophrenia(精神分裂症)and attention deficit hyperactivity disorder, or ADHD(注意力缺陷多动障碍), which are more common in left-handed people.
    Other recent research suggests that mixed-handedness—using different hands for daily tasks and not having a dominant one—may be even more strongly linked than left-handedness to ADHD and possibly other conditions.
    About 10% of people are left-handed, according to expert estimates. Another 1% of the population is mixed-handed. What causes people not to favor their right hand is only partly due to genetics—even identical twins, who have 100% of the same genes, don’t always share handedness.
    More important, researchers say, are environmental factors—especially stress—in the womb. Babies born to older mothers or at a lower birth weight are more likely to be lefties, for example. And mothers who were exposed to unusually high levels of stress during pregnancy are more likely to give birth to a left-handed child. A review of research, published in 2009 in the journal Neuropsychologia, estimated that about 25% of the variability in handedness is due to genetics.
    On average there is no significant difference in IQ between righties and lefties, studies show, betraying popular perceptions. There is some evidence that lefties are better at divergent thinking, or starting from existing knowledge to develop new concepts, which is considered an element of creativity. And left-handed people have salaries that on average are about 10% lower than righties, according to recent research performed at Harvard University that analyzed large income data bases, although findings of some earlier studies were mixed.
    Left-handedness appears to be associated with a greater risk for a number of psychiatric and developmental disorders. While lefties make up about 10% of the overall population, about 20% of people with schizophrenia are lefties, for example. Links between left-handedness and dyslexia, ADHD and some mood disorders have also been reported in research studies.
    The reasons for this aren’t clear. Scientists speculate it could be related to a concept known as brain lateralization. The brain has two halves. Each performs primarily separate, specialized functions, such as language processing, which mainly takes place in the left hemisphere. There is lots of communication between the hemispheres.
Having the knowledge of handedness can______.
选项 A、allow us to know clearly about how our brains work
B、make us understand the secret of brains’ interconnection
C、explain how some people have special diseases as their brains develop
D、offer us a stage where we can exchange information about brains
答案C
解析 细节辨认题。第二段阐述了偏手性的研究价值：为了解大脑的线路传输方式提供一个窗口；有助于解释与大脑发育有关的一些疾病，如诵读困难症、精神分裂症等。这些疾病为精神和发育方面的疾病，是伴随大脑发育过程产生的，因此C)正确。A)“偏手性可以使我们清楚了解大脑如何运作”是原文中的“偏手性为了解我们大脑的线路传输方式提供了一个窗口”的夸大说法，故排除；B)“偏手性让我们了解大脑间相互连接的奥秘”在原文中没有提及，故排除；D)“偏手性为我们交流有关大脑的信息提供平台”偏离主题，故排除。
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