Exercise seems to be good for the human brain, with many recent studies suggesting that regular exercise improves memory and thinking skills. But an interesting new study asks whether the apparent cognitive benefits from exercise are real or just a placebo effect — that is, if we think we will be “smarter” after exercise, do our brains respond accordingly? The answer has significant implications for any of us hoping to use exercise to keep our minds sharp throughout our lives.

　　体育锻炼似乎对大脑有益，最近的许多研究表明，经常锻炼可以改善记忆和思维能力。但一项有趣的新研究却提出了这样的问题：体育锻炼在提高认知能力方面显现出来的益处，是真实存在，还是心理作用？也就是说，假如我们相信自己在运动之后会“更聪明”，我们的大脑会不会做出相应的反应？对于想要通过锻炼来在一生中保持头脑敏捷的人来说，这个问题的答案至关重要。

　　In experimental science, the best, most reliable studies randomly divide participants into two groups, one of which receives the drug or other treatment being studied and the other of which is given a placebo, similar in appearance to the drug, but not containing the active ingredient.

　　在实验科学中，最出色可靠的研究会把参与者随机分为两组，一组得到正在研究的药物或治疗方法，另一组得到的则是无效的安慰剂，其外观与第一组拿到的药物类似，但不含活性成分。

　　运动真的能让我们变聪明吗

　　Placebos are important, because they help scientists to control for people’s expectations. If people believe that a drug, for example, will lead to certain outcomes, their bodies may produce those results, even if the volunteers are taking a look-alike dummy pill. That’s the placebo effect, and its occurrence suggests that the drug or procedure under consideration isn’t as effective as it might seem to be; some of the work is being done by people’s expectations, not by the medicine.

　　安慰剂很重要，因为它们帮助科学家来控制受试者的预期。例如，如果人们相信一种药物会产生某些效果，他们的身体可能就会出现相应的反应，即使志愿者只是吃了外观相似的无效药物。这就是安慰剂效应，它的存在意味着，正在研究的药物或疗程并没有看上去那么有效；有些效果是由人们的期待促成的，而不是药物本身。

　　Recently, some scientists have begun to question whether the apparently beneficial effects of exercise on thinking might be a placebo effect. While many studies suggest that exercise may have cognitive benefits, those experiments all have had a notable scientific limitation: They have not used placebos.

　　最近，一些科学家开始怀疑，体育锻炼表现出来的改善思维的益处可能是安慰剂效应。尽管许多研究显示，运动或有提高认知能力的好处，但这些实验都存在一种明显的科学局限性：它们没有使用对照组。

　　This issue is not some abstruse scientific debate. If the cognitive benefits from exercise are a result of a placebo effect rather than of actual changes in the brain because of the exercise, then those benefits could be ephemeral and unable in the long term to help us remember how to spell ephemeral.

　　这个问题本身并不涉及什么深奥的科学辩论。如果运动提高认知能力的益处是安慰剂效应，而不是大脑因为运动发生了真正的改变，那么这些好处可能就会转瞬即逝，无法长期帮助我们记住“转瞬即逝”这种复杂词汇。

　　Studying this issue, however, is difficult. There is no placebo for exercise and no way to blind people about whether they are exercising. They know if they are walking or cycling or not.

　　然而，研究这个问题却很困难。对于体育锻炼来说，不存在无效对照剂，也没有办法不让受试者知道自己是不是在运动。他们清楚自己有没有步行或骑自行车。

　　So researchers at Florida State University in Tallahassee and the University of Illinois at Urbana-Champaign came up with a clever workaround. They decided to focus on expectations, on what people anticipate that exercise will do for thinking. If people’s expectations jibe closely with the actual benefits, then at least some of those improvements are probably a result of the placebo effect and not of exercise.

　　因此，来自塔拉哈西的佛罗里达州立大学(Florida State University)以及伊利诺伊大学厄巴纳-香槟分校(University of Illinois at Urbana-Champaign)的研究人员想到了一个聪明的迂回办法。他们决定把关注点放在：受试者预期锻炼会对思维产生何种影响。如果他们的期待与实际的益处吻合，那么至少部分好处很可能是源于安慰剂效应，而不是锻炼的结果。

　　The scientists had seen this situation at work during an earlier study of video games and cognition. Past research had suggested that playing action-oriented video games improves players’ subsequent thinking skills. But when scientists in the new study asked video-game players to estimate by how much the games would improve their thinking, the players’ estimates almost exactly matched the gains seen on cognitive tests after playing. In other words, the cognitive benefits of playing video games appear to be largely a result of a placebo effect.

　　在早前对视频游戏与认知能力的关系所做的研究中，科学家们就遇到过这种情况。过去的研究显示，玩动作类视频游戏可以改善玩家的思维能力。但当进行新研究的科学家们让视频游戏玩家估计游戏能在多大程度上改善他们的思维能力时，玩家的估计几乎和玩后的认知测试的加分完全吻合。换句话说，玩视频游戏的认知好处似乎主要是心理作用。

　　For the new study, which was published last month in PLOS One, the researchers repeated this experiment but focused on exercise. Recruiting 171 people through an online survey system, they asked half of these volunteers to estimate by how much a stretching and toning program performed three times a week might improve various measures of thinking, including memory and mental multitasking.

　　关于锻炼的这项新研究上个月发表在《公共科学图书馆：综合》期刊(PLOS One)上。研究人员重复了这个实验，但把实验内容换成了体育锻炼。他们通过一个在线调查系统招募了171人，要求其中一半的志愿者来评估，如果一周进行三次拉伸运动，能够在多大程度上改善思维能力，比如记忆力和一心多用的能力。

　　The other volunteers were asked the same questions, but about a regular walking program.

　　另一组志愿者被问到同样的问题，不过锻炼项目换成了有规律的步行运动。

　　In actual experiments, stretching and toning regimens generally have little if any impact on people’s cognitive skills. Walking, on the other hand, seems to substantially improve thinking ability.

　　在真实的实验中，拉伸运动基本上对认知能力没有多少影响。另一方面，散步则显示出能大幅改善思维能力。

　　But the survey respondents believed the opposite, estimating that the stretching and toning program would be more beneficial for the mind than walking. The volunteers’ estimates of the likely cognitive improvements from gentle toning averaged about a three on a scale from one to six. The estimates of benefits from walking were lower.

　　不过，在这项实验中，受试者的想法则正好相反。他们估计拉伸项目比步行对大脑更有益处。以1到6级来衡量，志愿者认为，轻度拉伸对认知的潜在改善的平均等级是3。他们对步行的评估则低一些。

　　These data, while they do not involve any actual exercise, are good news for people who do exercise. “The results from our study suggest that the benefits of aerobic exercise are not a placebo effect,” said Cary Stothart, a graduate student in cognitive psychology at Florida State University, who led the study.

　　这些数据虽然没有涉及真正的体育锻炼，对于真正从事锻炼的人来说却是个好消息。“我们的研究结果显示，有氧运动的好处不是安慰剂效应，”佛罗里达州立大学的认知心理学研究生卡里·斯托塔特(Cary Stothart)说。他牵头进行了这项研究。

　　If expectations had been driving the improvements in cognition seen in studies after exercise, Mr. Stothart said, then people should have expected walking to be more beneficial for thinking than stretching. They didn’t, implying that the changes in the brain and thinking after exercise are physiologically genuine.

　　斯托塔特解释，假如是人们的期待在驱动研究中发现的锻炼对认知能力的改善，那么受试者就应该是期待步行比拉伸更有益处。他们没有，这就意味着体育锻炼之后，大脑和思维能力真的发生了生理上的变化。

　　Of course, this study was small and involved a self-selected group of people who happen to like completing online surveys. Some said they exercised, others said they did not. None claimed to be familiar with the science related to exercise and the brain, but it is impossible to know if people were being forthright.

　　当然，这项研究的规模较小，参与者只涵盖了喜欢完成网上调查的人。有些人声称自己平时锻炼，其他人则说自己不运动。没人自称熟悉与运动和大脑有关的科学，但也无法知道他们是不是都说了真话。

　　Still, the findings are strong enough to suggest that exercise really does change the brain and may, in the process, improve thinking, Mr. Stothart said. That conclusion should encourage scientists to look even more closely into how, at a molecular level, exercise remodels the human brain, he said. It also should spur the rest of us to move, since the benefits are, it seems, not imaginary, even if they are in our head.

　　不过，斯托塔特表示，这些发现仍然足以证明，锻炼真的会改变大脑，或许在这个过程中，还可能改善思维能力。他说，这个结论应该可以鼓励科学家们进一步探索：在分子层面上，运动是如何重塑了我们的大脑。它还应该激励我们其他人动起来，因为看来这些益处并非想象出来的，虽然它们的确发生在我们的大脑里。