AAccording to the latest figures, the majority of the world`s population is now bilingual or multilingual, having grown up speaking two or more languages. In the past, such children were considered to be at a disadvantage compared with their monolingual peers. Over the past few decades, however, technological advances have allowed researchers to look more deeply at how bilingualism several clear benefits of being bilingual.

A根据最新教据显示，世界上的大多数人口现在都使用两种或多种语言，说着两种或多种语言长大：过去，与只说一种语言的同龄人相比，这些孩子被认为处于劣势、然而，在过去的几十年里，科技的进步使得研究者们可以深入地研究使用双语是如何影响和改变认知和神经系统的，从而证实了使用双语的一些显著好处。

B研究表明当一位双语使用者使用一种语言时，另一种语言同时也会被激活当我们听到一个单词时，我们并不是一次听全整个单词：单词中的每个音是有相继次序的..在听完整个单词之前，大脑的语言系统开始猜测那个单词可能是什么至少在辨别发音的初期，如果你听到“ can”，你可能会下意识地猜到“ candy••或者“ candle"等词，对于双语使用者来说，这种激活并不仅限于单一词语，不论单词所属的语言是什么，听觉输入会激活相应的单词：对于这一现象，最有乃的证据来自于被称为"语言协同激活效应”的眼动研究一位俄语和英语的使用者楗要求在一组物品中“拿起 marker”，他会比不说俄语的人之久地关注蟀票.因为诙语中表示邮票的单词是 “ marka”，听起来像他听到的英语单词 “marker”在类句的案例中，语言协同激活效应的出现是因为听的人可以把听到的单词玦射到他们所讲的任一种语言的单词上。

BResearch shows that when a bilingual person uses one language, the other is active at the same time. When we hear a word, we don`t hear the entire word all at once: the sounds arrive in sequential order. Long before the word is finished, the brain's language system begins to guess what that word might be. If you hear `can', you will likely activate words like 'candy` and 'candle` as well, at least during the earlier stages of word recognition. For bilingual people, this activation is not limited to a single language; auditory input activates corresponding words regardless of the language to which they belong. Some of the most compelling evidence for this phenomenon, called 'language co-activation`, comes from studying eye movements. A Russian-English bilingual asked to 'pick up a marker` from a set of objects would look more at a stamp than someone who doesn't know Russian, because the Russian word for 'stamp`, marka, sounds like the English word he or she heard, 'marker`. In cases like this, language co-activation occurs because what the listener hears could map onto words in either language.

C然而，应对这种持续的语言选择可能会导致一些困难例如，了解一种以上语言会使说话者说出图片的速度变慢，并且会出现“话到嘴边想不起词”的情况，就是你几乎可以但还是想不起一个词来所以，同时使用两种语言需要人们在特定的时间控制好对语言的应用程度。因此，双语使用者通常在那些需要冲突管理的任务上表现得更好。在经典的字色混淆任务中，人们看到一个单词并被要求说出这个单词字体的颜色与字色不对应时 ( 例如单词“ red”被印刷成蓝色 )相比，当字色对应时 (例如单词 “red”被印刷成红色)，参加者会更快地准确说出单词。这种情况出现是因为单词本身 ( red)和它的颜色(蓝色)冲突：双语使用者通常在这类任务中表现更好，他们有忽略矛盾的视频信息的能力，这使他们专注于输入信息中的相关内容。双语使用者同样在两种任务转换中表现得更好;例如，当双语使用者要在将物体按顏色(红色或蓝色)分类的任务中转换到按形狀(圆形或三角形)时，他们比单一语言使用者要做得更快，这反映出当需要快速改变策略时，他们有更好的认知控制能力。

D看起来双语优势在神经系统上的根源似乎也延伸到了之前人们普遍认为的脑部感觉处理区域。当单语和双语的青少年在没有任何背景嗓音干扰的情况下听简单的说话声，他们的脑千反应高度相似。然而，当研究者在有背景噪音的情况下，给两组实验对象放同样的声音时，双语使用者的神经反应要大得多，这反映了他们对声音的基本频率有更好的编码，这种频率是一种与音高识别密切相关的声音特征。

CHaving to deal with this persistent linguistic competition can result in difficulties, however. For instance, knowing more than one language can cause speakers to name pictures more slowly, and can increase 'tip-of-the-tongue states`, when you can almost, but not quite, bring a word to mind. As a result, the constant juggling of two languages creates a need to control how much a person accesses a language at any given time. For this reason, bilingual people often perform better on tasks that require conflict management. In the classic Stroop Task, people see a word and are asked to name the colour of the word`s font. When the colour and the word match (i.e., the word `red` printed in red), people correctly name the colour more quickly than when the colour and the word don`t match (i.e ., the word `red' printed in blue). This occurs because the word itself (`red`) and its font colour (blue) conflict. Bilingual people often excel at tasks such as this, which tap into the ability to ignore competing perceptual information and focus on the relevant aspects of the input. Bilinguals are also better at switching between two tasks; for example, when bilinguals have to switch from categorizing objects by colour (red or green) to categorizing them by shape (circle or triangle},they do so more quickly than monolingual people,reflecting better cognitive control when having to make rapid changes of strategy.

E这种在认识和感觉处理中的提升可能会帮助一个双语使用者在环境中处理信息，也解释了为什么与成年单一语言使用者掌握第二种语言相比，成年双语使用者能更好地习得第三种语言。这种优势可能根源于他们有能力专注新语言的信息而减少已有语言的千扰。

F研究还表明双语经验可以帮助认知机制保持灵敏，这是通过利用其他脑部网络来弥补衰老受损部分来实现的。相比单一语言使用者，年龄较大的双语使用者拥有更好的记忆力，这会带来现实中的健康益处。在一项对超过200名阿尔茨海默氏症(一种大脑退化性疾病)患者的研究中，双语病人最初报告疾病症状的时间比单语使用者平均晚五年。在一项追踪研究中，研究者对比了阿尔茨海默氏症严重程度相同的双语和单语病人的大脑。令人吃惊的是，双语使用者的大脑比单一语言使用者有更多的疾病特征，尽管他们的外在行为和能力是一样的。如果大脑是一个引擎，那么在同样容量的燃料下，双语使用者会帮助它走得更远。

DIt also seems that the neurological roots of the bilingual advantage extend to brain areas more traditionally associated with sensory processing. When monolingual and bilingual adolescents listen to simple speech sounds without any intervening background noise, they show highly similar brain stem responses. When researchers play the same sound to both groups in the presence of background noise, however, the bilingual listeners` neural response is considerably larger, reflecting better encoding of the sound`s fundamental frequency, a feature of sound closely related to pitch perception.

G此外，双语经验的好处似乎体现得很早。在一项研究中，研究者教在使用单一语言或双语家庭生长的七个月大的婴儿，当他们听到叮当声时，一个木偶就会出现在屏幕的一侧。在研究进行到一半时，木偶出现在屏幕的另一侧。为了得到奖励，婴儿必须使用他们学到的规则;只有双语婴儿能够成功学到新规则。这表明，对于年龄小的儿童以及年龄更大的人来说，在多语言的环境中成长带给他们的优势远远不止语言本身。

ESuch improvements in cognitive and sensory processing may help a bilingual person to process information in the environment, and help explain why bilingual adults acquire a third language better than monolingual adults master a second language. This advantage may be rooted in the skill of focussing on information about the new language while reducing interference from the languages they already know.

FResearch also indicates that bilingual experience may help to keep the cognitive mechanisms sharp by recruiting alternate brain networks to compensate for those that become damaged during aging. Older bilinguals enjoy improved memory relative to monolingual people, which can lead to real-world health benefits. In a study of over 200 patients with Alzheimer`s disease, a degenerative brain disease, bilingual patients reported showing initial symptoms of the disease an average of five years later than monolingual patients. In a follow-up study,researchers compared the brains of bilingual and monolingual patients matched on the severity of Alzheimer`s symptoms. Surprisingly, the bilinguals` brains had more physical signs of disease than their monolingual counterparts, even though their outward behaviour and abilities were the same. If the brain is an engine, bilingualism may help it to go farther on the same amount of fuel.

GFurthermore, the benefits associated with bilingual experience seem to start very early.In one study, researchers taught seven-month-old babies growing up in monolingual or bilingual homes that when they heard a tinkling sound, a puppet appeared on one side of a screen. Halfway through the study, the puppet began appearing on the opposite side of the screen. In order to get a reward, the infants had to adjust the rule they`d learned; only the bilingual babies were able to successfully learn the new rule. This suggests that for very young children, as well as for older people, navigating a multilingual environment imparts advantages that transfer far beyond language.