左撇子、右撇子和混合用手者：大脑不对称性的心理学，与Sebastian Ocklenburg博士

我们生活在一个为右撇子设计的世界里。如果你是左撇子，你一定深有体会：寻找左撇子剪刀或书写时不晕染的钢笔有多痛苦。尽管课桌、开瓶器和罐头起子的设计者常常忽略左撇子，但他们始终是人口中稳定存在的小众群体。今天，我们将对话一位研究用手习惯及大脑偏侧化其他方面的心理学家，探讨用手习惯的起源及其揭示的大脑组织方式。那么，用手习惯究竟为何存在？

We live in a world designed for right handed people. If you're a lefty, you know the pain of trying to track down left handed scissors or a pen that won't smudge as you write. Yet despite being overlooked by the designers of school desks, corkscrews and can openers, lefties make up a small but consistent part of the population. Today, we're going to talk to a psychologist who studies handedness and other aspects of brain lateralization about handedness, where it comes from, and what it can tell us about how the brain is organized. So why does handedness exist in the first place?

为何右撇子比左撇子更普遍？用手习惯如何及何时形成？这是由基因决定、早期生活经历影响，还是两者共同作用？左撇子更具创造力的刻板印象是否有依据？神经多样性人群是否更可能是左撇子？

Why is it more common to be right handed than left handed? How and when does handedness develop? Is it genetically determined due to early life experiences or maybe a combination of the two? Is there any truth to the stereotype that lefties are more creative than other people? Are neurodivergent people more likely to be left handed?

其他动物是否存在用手（或用爪）偏好？为何左撇子在脑科学研究中常被忽视？欢迎收听《心理学漫谈》——美国心理学会旗舰播客节目，探索心理科学与日常生活的联系。我是主持人金·米尔斯。今天的嘉宾是塞巴斯蒂安·奥克伦伯格博士。

Does handedness or pawedness exist in other animals? And why are left handed people often underrepresented in brain research? Welcome to Speaking of Psychology, the flagship podcast of the American Psychological Association that examines the links between psychological science and everyday life. I'm Kim Mills. My guest today is Doctor.

奥克伦伯格博士现任德国汉堡MSH医学院心理学研究方法教授，专注于大脑语言和运动系统的半球不对称性研究，包括用手习惯。他探究了不对称性的发展机制，涉及遗传与表观遗传因素、脑不对称性的神经生理学基础，以及人类用手偏好与其他动物肢体偏好的普遍性。奥克伦伯格博士著有大量同行评议期刊论文及专著《偏侧化大脑：半球不对称性的神经科学与进化》。

Sebastian Auchlenberg, a professor of research methods in psychology at MSH Medical School in Hamburg, Germany. His research focus on hemispheric asymmetries in the brain's language and motor systems, including handedness. He has looked at how asymmetries develop, including genetic and epigenetic factors and the neurophysiology of brain asymmetries in the prevalence of handedness in humans and limb preferences in other animals. Doctor. Ochlenberg is the author of many peer reviewed journal articles, as well as the book The Lateralized Brain: The Neuroscience and Evolution of Hemispheric Asymmetries.

他还在《今日心理学》开设博客专栏《左与右的心理学与神经科学》。奥克伦伯格博士，感谢您今日参与节目。

He also writes a blog for Psychology Today called The The Psychology and Neuroscience of Left and Right. Doctor. Ocklenberg, thank you for joining me today.

谢谢金，非常荣幸受邀。

Thank you Kim. I'm very happy to be here.

让我们从基础数据开始——左撇子有多普遍？全球左撇子人口占比是多少？

Well let's start by talking about how common is left handedness. What percentage of the population is left handed?

全球最大规模的元分析研究表明，左撇子的最佳估计比例为10.6%。这个数字会因地区略有差异，有些国家的比例稍低，有些则略高，最高可达19%左右。但世界上没有任何国家的左撇子比例超过20%，所以他们始终是少数群体。

So the largest meta analyzers worldwide have showed that the best estimate is ten point six percent of left handed people. That varies a little bit depending on location, so there are some countries where the number is a little bit lower. There are some countries where it goes a little bit higher, up to, like, 19%, but there's no country in the world where there are more than 20% left handers, so they're always a minority.

为什么有些国家的比例会更高？影响因素是什么？

Why might some countries have higher percentages? What's in play?

我认为这主要与文化因素有关。你可能记得几十年前美国曾有过'用手习惯改造'的做法，学校里会鼓励左撇子儿童用右手写字。现在大多数国家已不再这样做，但仍有部分国家对左撇子存在负面刻板印象。这些国家的左撇子比例通常较低，因为教师会鼓励左撇子儿童使用右手写字。而从未进行过这种改造的国家，比如某些斯堪的纳维亚国家，比例往往略高——在这些国家，即使老一辈人中通过客观测试被判定为左撇子的比例也更高。

I think this has something to do with mostly cultural factors. You may remember that a couple decades ago in The US there was something called handedness retraining. In schools, left handed kids were encouraged to use the right hand for writing. We don't do this anymore in most countries, but there are still some countries where there are sort of negative stereotypes against left handed people. And those countries typically have somewhat lower numbers of left handers because, for example, teacher encouraged left handed kids to write with the right hand, while countries that never had this relearning, for example, some Scandinavian countries, they tend to have, like, a little bit higher rates because in those countries also in the older generation, there are more people that are classified as left handed in objective tests.

这引出了用手习惯决定因素的问题。是基因决定的吗？与产前或早期生活经历有关？还是其他因素？

And that raises the question of what determines handedness. Is it genetic? Is it related to prenatal or early life experiences? Or is it something else?

如今我们知道用手习惯是个相当复杂的问题。过去人们认为存在一个用手基因来决定，现在可以确定基因因素确实起作用。比如观察父母的用手习惯就能预测孩子的用手倾向——两个左撇子父母生出左撇子孩子的概率高于两个右撇子父母。但分子遗传学技术显示，这些基因因素只能解释约四分之一的用手习惯。

We know today handedness is a quite complicated thing. So back in the day people thought there is a handedness gene and that determines handedness, and we know genetic factors for certain play a role. So for example, if you look at parents and their handedness, it predicts the handedness of children. So two left handed parents have a higher chance of having a left handed child compared to two right handed parents. But, like, molecular genetic techniques showed that the actual amount of handedness that can be explained by these genetic factors is around a quarter.

也就是说25%的用手习惯基本由基因决定，而且我们知道这不是单个基因的作用。根据大型同行评审研究，约有48个不同基因参与其中。这是个非常多元化的表型。有趣的是，这些基因与手部毫无关联，它们主要影响大脑发育——这也是人们注意到的现象。

So 25% of handedness basically is genetic, and we know it is not one gene. It's about 48 different genes that play a role according to large peer reviewed studies. So it's a very multifaceted phenotype. And those genes have, interestingly enough, nothing to do with the hands. They're mostly relevant for brain development, and that's also something, people notice.

对吧？如果你只看左撇子或右撇子的手，根本无法判断其用手习惯。因为用手习惯不是由手部决定的，而是由大脑决定的，具体来说是由控制运动的脑部运动皮层决定的。

Right? So if you just look at the hands of a left hander or a right hander, you cannot tell whether the person is left or right handed. That is because handedness is not caused by the hands. It's caused by the brain. It's specifically caused by the motor cortex of the brain, so the area that controls the movements.

我们知道右运动皮层控制身体的左半部分，反之亦然。原则上，用手习惯代表了我们所说的半球优势。这是对精细运动行为的半球优势，比如写字、木雕、绘画等。所有需要用手完成的复杂动作，比投掷棒球这类动作更复杂。人们对此有主导优势。

And we know that the right motor cortex is controlling the left half of the body and vice versa. And handedness in principle represents something what we would call a hemispheric dominance. It's a hemispheric dominance for fine motor behavior, things like writing, things like wood carving, drawing. So everything that's, like, complicated to do with the hands, it's more complicated than, like, throwing a baseball or things like that. And people have a dominance for that.

因此，左撇子的右运动皮层主导精细运动行为，而右撇子则是左运动皮层。这是其中一部分。与大脑发育相关的基因也与用手习惯有关。除此之外，还有其他因素如环境因素似乎也起作用。一个有趣的现象是大规模研究表明，男性比女性更常是左撇子，这表明性激素如睾酮可能有一定影响。

So left handers, for these people, the the right, motor cortex is dominant for my fine motor behavior, and for right handedness, the left. So, this is the the the one part. So genes relevant for brain development are relevant for handedness. In addition to that, there are also other factors like environmental factors, that seem to play a role for handedness. One thing, that's quite interesting is that large scale studies could show that men are more often left handed than women, which suggests there is a role of sex hormones like testosterone.

还有一些产前因素与左撇子有关，例如母乳喂养、双胞胎出生等，以及其他几个因素。这里也讨论了激素效应。

There are also a couple of prenatal factors that have been associated with left handedness, for example, being breastfeed plays a role, being in the twin birth plays a role, and several other factors. And also here, hormonal effects are discussed.

用手习惯在生命的哪个阶段开始显现？我是说，你能判断一个小婴儿将来会是右撇子还是左撇子吗？

How early in life does handedness emerge? I mean, can you tell whether a little baby is gonna be right handed or left handed?

我可以以相当高的概率判断。虽然每个人显现的时间点不完全相同，但有非常有趣的研究。人们使用高科技超声波记录观察母亲子宫中的胎儿，看他们喜欢吮吸哪只拇指或喜欢用哪只手臂互动。甚至在出生前，人类就对某一侧有强烈偏好。如果等几年后这些婴儿出生并上小学，大约六岁左右开始学习写字时测试，可以从超声波中显示的吮吸拇指或运动的偏好手，以超过96%的概率预测写字时的惯用手。

I can with a pretty high chance. So it does not emerge at exactly the same time point for everyone, but there's quite fascinating research on that question. So, people used very high-tech ultrasound recordings to look at unborn babies in a mother's womb and looked at which thumb they like to suck or which arm they like to interact with. And now you can see even before birth, humans have a strong preference for one side. And if you then just wait a couple of years and then test these babies after they've been born and after they went to primary school, and you test them at, like, around age six or so when you start to learn writing, you can predict the preferred hand for writing with a more than 96% chance from the hand that is preferred in the ultrasound for, like, thumb sucking or movement.

因此，我们可以从这项研究中看出，对于绝大多数人来说，用手习惯在出生时甚至出生前就已经基本确定了。

So we can tell from that research that for a large, large amount of people, handedness is already pretty much determined at birth or even before.

为什么右撇子比左撇子更常见？我们甚至知道原因吗？

Why is it more common for people to be right handed than left handed? Do we even know?

这是个好问题，但我们尚不清楚答案。目前没有公开发表的心理学研究能确切解释为何人类右侧比左侧更为平静。有一些假设观点，有趣的是当我们观察动物时，比如对猫狗进行大规模偏侧性研究时，通常会发现左撇子（或左前肢主导）的情况比人类普遍得多。虽然动物也表现出偏侧性，但人类这种10.6%左撇子和89.4%右撇子的极端偏态分布似乎非常独特。关于为何右撇子占据绝对优势，心理学界提出过多种理论解释。

That is a good question, and we don't know. There is no published psychological research that ever answered this question why it is specific to right side that's more calm than the left in humans conclusively. There is a couple of ideas, and what's quite interesting is when we, for example, look at animals, we did large meter studies on partners in cats and dogs. You typically find that left handedness or left partners in that case, it's much more common than in humans. So while animals also show handedness, this very skewed distribution with the ten point six left handers and 89.4% right handers in humans seems to be pretty unique, and there have been several psychological theories why it could be the case that we have this, yeah, very high preponderance of right handedness.

其中一个解释是：人类显然需要从他人那里学习复杂动作行为。比如父亲教孩子系鞋带，如果双方使用相同的手部操作，教学会更容易。这个原理同样适用于任何工作相关技能或需要手工操作的生产活动。

And one idea why that is is that, obviously, human beings learn very complicated motor behaviors from other people. Right? So example, a dad might explain his kid how to tie their shoes. That's, of course, easier if the dad uses the same hand for explaining than the kid uses for tying the shoe himself. The same goes for any sort of work related thing, any sort of, like, production with manual activities.

因此与多数人保持相同利手性存在优势——这能简化动作技能的学习过程，这也是解释人类右撇子占绝对多数的理论之一。

So there seems to be a benefit from having the same handedness as other people because it makes this motor learning easier, which is one of the ideas why there are so many right handers in humans.

不过我在想，从进化角度看，双手灵巧性似乎应该是更有利的特征，但现实中却并不常见。为什么没有更多人具备双手灵巧能力呢？

I'm just wondering, though. It would seem to me that ambidexterity would be something that evolution would have favored, and yet it doesn't seem to be common. Why aren't more people ambidextrous?

要回答这个问题，我们需要先思考人类大脑为何存在这些功能不对称性。众多构成人类特征的认知功能、情感体验等都呈现大脑单侧化表征。最典型的例子当属语言功能——绝大多数人的语言神经网络位于左脑半球。平时我们难以察觉这点，但当家人遭遇中风时就会明显显现。

So I think in general, in order to answer that question we have to think a little bit about why do humans have these brain asymmetries in the first place. So we know there are a lot of cognition, a lot of emotion, a lot of other things that makes us human are asymmetrically represented in the brain. Most common example would, of course, be language. So the language networks are in the vast majority of people in the left hemisphere of the brain. And most of the time, we will not notice this, but we notice it very much if you, for example, have a family member that suffers a stroke.

比如左脑中风患者常出现严重语言障碍甚至失语，而右脑中风则不会。你可能会问：如果双脑半球都能控制语言不是更好吗？问题在于人类日常执行的许多行为极其复杂，需要大量神经组织参与运作。

Right? Somebody has a stroke in the left hemisphere. They often have severe language issues and then can't talk anymore, and that doesn't happen after a stroke in the right hemisphere. Now you may argue, wouldn't it be better if both hemispheres would be able to control language? The problem with that is a lot of the things we're doing on everyday basis as humans are quite complicated, and they lead a lot of neural tissue to be performed.

若语言功能在双脑均等分布，我们可能需要更大的脑容量，这将带来诸多弊端。比如分娩时人类需要更早出生等等。因此进化压力促使大脑运作高效化——通过分工机制最优利用有限神经元。我认为这就是多数功能单侧化分布的根本原因，也是为什么极少人真正具备双脑语言功能或双手同等灵活性——科学测量显示，真正的双手灵巧性其实极其罕见。

So if we had the language represented equally in both sides of the brain, we would likely need larger brains, and that, of course, would have a lot of disadvantages. For example, when it comes to birth, the human would be needed to to be born even earlier as they are now and so on and so on. So there seems to be a evolutionary force towards making brains efficient. So it's a division of labor that makes optimal use of the neurons we have in our head. I think this is the main reason why so many things are asymmetrically organized and why it's not generally come that people have language on two sides or are equally dexterous with with both hands because the ambidexterity, like true ambidexterity measured with scientifically accurate methods is something that is extremely rare.

在这项研究中，我们确实对所谓的混合用手和双手灵巧做了区分。大多数人几乎在所有活动中都使用右手，有些人则主要使用左手。还有些人介于两者之间。比如你可能认识一些人用左手写字、画画，却用右手投棒球或拿扫帚等等。

So in head on this research, we do distinguish a little bit between what we call mixed handed and what we call ambidextrous. So a lot of people would use the right hand for pretty much everything they do, and some people use the left hand for pretty much everything they do. And there are some that are in between. Right? So you may know some people that, for example, write with the left, and they draw with the left, but then they throw a baseball with the right and use a broom with the right and so on.

但这些人都不是真正的双手灵巧者，他们只是混合惯用手。明白吗？他们某些活动用左手更擅长，某些则用右手。要成为真正的双手灵巧者，必须左右手在准确性和速度上都完全相当。

These people, however, they're not ambidextrous. They're mixed standard. Right? They can do certain activities better with the left hand and certain activities better with the right hand. For someone to qualify as truly ambidextrous, that person would be equally as accurate and equally as fast with both the left hand and the right hand.

以写字为例，这种情况极为罕见。关于双手灵巧的大型研究不多，但我们估计约占人口的千分之一。这通常与主动训练有关，比如有些网球选手会刻意训练非惯用手来增加比赛中的突然性。

And this is, for example, for writing extremely rare. There's not a lot of really big studies on ambidexterity, but we would estimate it's about zero point one percent of the population, so roughly one in a thousand people. And it often has a lot to do with people training this actively, right? So there are some people who wanna be ambidextrous. For example, it's something like tennis players sometimes do.

但研究发现，许多自认双手灵巧的人，经过标准心理手部技能和偏好测试后，其实只是混合惯用手。真正的双手灵巧需要左右手在各项任务中表现完全对等。

They actively train the the nondominant hand to be, like, more surprising in the game and so on and so on. But what we often find is that a lot of people who think they are ambidextrous, if you actually test them and you do, like, a couple of standard psychological hand skill and hand preference task, they do not turn out to be ambidextrous. They turn out to be mixed standard.

现在我们将短暂休息。回来后我将与Acklenburg博士探讨：侧化现象是否在动物中普遍存在，如何判断宠物是左撇子还是右撇子。刚才我们谈到动物的用手（或爪）偏好，这种现象仅存在于哺乳动物吗？动物界的偏侧性表现是怎样的？

We're going to take a short break now. When we return, I'll talk with doctor Acklenburg about whether lateralization is also common in animals and how to tell if your pet is left or right pawed. And we talked a moment ago about handedness or pawedness in in animals. Are they only mammals that exhibit this, and and what does asymmetry look like across the animal kingdom?

是的。过去人们认为偏侧性仅为人类特有，这完全错了。我们通过大规模比较研究发现，动物表现出某种偏好是普遍规律——无论是猫狗的爪偏好还是海龟的鳍偏好。这种不对称性甚至存在于最原始的生物中，比如没有四肢的秀丽隐杆线虫，其嗅觉神经元就呈现不对称分布。

Yes. So people thought back in the day that that handedness is something that's only been shown by Jungs, and they could not have been more wrong. So in general, we could show in a large scale study where we compared findings from studies looking at partners and other forms of limp preferences in animals that it is the rule, not the exception, that animals show some sort of preference, whether that be partners in cats or dogs or flippantness in turtles. There is a wide variety of these asymmetries, and, it can show, obviously, on a behavioral level, but it can also show in other things. For example, the most primitive organism that has been shown to show asymmetries is actually a worm that doesn't even have limbs, say elegans.

这似乎是大神经组织进化的核心原则。人类的特殊之处在于：我们的偏侧性极为强烈——不仅右利手占绝对优势，语言功能也呈现显著单侧化。这可能源于人类复杂的语言和运动行为需要大量神经组织，进化压力促使大脑通过强烈偏侧化来实现最高效运作。

And here it could be shown that neurons that were relevant for olfaction, so the worm smelling different different chemical substances, were asymmetrically organized. So we know in general that this seems to be a really core evolutionary principle of brain or nervous system organization. What's a little bit interesting in regard to humans is what I already said, that humans seem to be a little bit unique in the way that our asymmetries are very strong, that we have a a very strong handedness, very strong preference for the right hand, but also that we have a very pronounced language asymmetry, and we have many other forms of asymmetries. That may be the case because we're doing, quite complicated things with language and, motor behavior that other animals do not do in that sense. So it's a lot of neural tissue we need for that, so there's a strong pressure to make this as efficient as possible so we have strong asymmetries.

但总的来说，几乎所有被研究过的动物身上都能发现不对称性，这相当有趣。作为播客听众，如果你对此感兴趣，想观察自家宠物的偏好，可以尝试食物获取测试。比如用纸筒装一点猫粮或狗粮，观察动物用哪只爪子取出食物，重复五到六次。如果发现动物总是使用同一侧爪子，就能基本确定你的猫是左撇子还是右撇子。

But in general, you will find asymmetries in pretty much all animals people have looked at. That's quite interesting. You can also, if you're interested as a listener of that podcast, if you want to look into that in your pet, you could, for example, do something like a food reaching task. So if you have some sort of, like, paper roll and you put a little bit of cat food or dog food into that, and then you can look, which paw the animal would use to get the food out, then you can do that maybe like five or six times. And, if you notice your animal is always using, the same paw, you can be pretty sure your cat is left paw or right paw.

显然，动物还有许多其他偏好。比如可以观察它们的睡姿——猫咪蜷缩时偏向左侧还是右侧，当你把它们放进睡篮时的朝向等等。这种现象不仅深刻影响着人类生活，也存在于宠物和许多其他动物身上。

And, obviously, animals also have a lot of other preferences. So for example, you can look at things like their sleeping side. So if the cat curls up to the left or curls up to the right side, if you put them into their, like, little basket when you're sleeping, and many other things. So it is something that's not only affecting our lives with humans a lot, but also those of our pets and many other animals.

左撇子和右撇子的大脑结构看起来不同吗？是否存在解剖学差异？

Now do the brains of people who are left handed and right handed look different? Are they different structurally?

是的。在与用手习惯直接相关的大脑区域——比如运动皮层——存在结构差异。但其他多数脑区并无不同。那些认为左撇子智力更高或更低的猜测，都是没有根据的。

Yeah. They're different structurally in terms of the brain areas that are directly relevant to handedness. So they are their motor court, he says. They are not differently structured in a lot of other different brain areas. So these ideas that maybe left handers have, I don't know, higher or lower intelligence, that's not the case.

这种差异仅影响运动系统，反映在运动系统的结构中，但不会延伸到其他功能。我认为，与特定功能直接相关的脑区（比如控制书写能力的运动皮层）会显现变化，而其他脑区通常不会。

So it is something that affects the motor system. It's something that is reflected in the structure of the motor system, but it doesn't go beyond that. And I think that the brain areas that are directly relevant to a function, like the motor cortex that allow me is allowing me to write, they show changes. Many other brain areas typically don't.

很多人可能没意识到，我们身体其他部位也有偏好。除了左右手，我们还可能有惯用脚。那么左撇子是否更可能也是左脚或左眼优势呢？

Now a lot of people might not be aware, but we also favor other body parts. So we're not just left handed or right handed, but we might be left footed or right footed. But if you're left handed, are you more likely to be left footed or left eyed?

没错，这类行为不对称现象数量惊人。总有些未被注意的细节突然出现在新研究中，让人惊叹。人们确实存在惯用脚，用手习惯与用脚习惯确实相关，但非绝对。我们的大型研究表明，约65%的右撇子同时也是右脚优势者。

Yes, so there is a fascinating number of these behavioral asymmetries, and there's always, like, something people haven't thought of, and then there's a new research paper, and I'm like, wow. That's that's really cool. So, yes, people have a favorite foot, and, yes, headedness and footedness are related. They're not a 100% related. So we, had a large study on that showing that around sixty five percent of right handers are also right footed.

此外还存在这些感官偏好，比如人们会用偏好的耳朵听门声，或用偏爱的眼睛观察显微镜。我特别着迷的是，人们在各类社交触碰中也存在视觉不对称现象。比如击掌时，你会习惯用某只手；亲吻他人时，人们会强烈倾向于将头转向某一侧。

There are also these sensory biases, so people have a a favorite ear to listen to a door or, like, a favorite eye to look to a microscope. What I find very fascinating is also that people have sight asymmetries in different forms of social touch. Right? So for example, if you give somebody a high five, you have a preferred hand to give a high five. If people kiss another person, They have a strong preference to turn the head to one side.

若你尝试用相反方向亲吻他人会非常有趣——绝大多数参与者表示这感觉极其怪异。人们有偏好的拍打他人侧边，有偏好的食物品尝侧，同一食物在左右侧咀嚼时风味可能略有差异，诸如此类。这些行为上的不对称某种程度上反映了大脑古老的不对称性，至今仍在日常生活中随处可见。

It's quite interesting if you kiss, like, people to the left or the right side for all your life to try the other one. Most participants say that that's an extremely weird feeling. People have a favorite side to hack other people on. People have a favorite side to taste food on, so their favorite food tastes maybe a little bit different if you chew it on the left or on the right side, and so on and so on. So these asymmetries in behavior that, of course, reflect asymmetries in the brain to some extent, that are very ancient, they're, like, popping up left and right in everyday life, even today.

多数人根本不会注意到这些，因为他们甚至不会主动思考。但如果你在日常生活中稍加观察，特别留意那些可选择左右侧的行为，就会发现这些几乎不变的偏好。你不会突然改用左侧拥抱习惯右侧拥抱的人——这些都是根深蒂固的行为偏好。

And most people don't don't really notice it because they don't, like, even actively think about it. But if you really monitor yourself a little bit when you're going through your day and you just actively pay attention to behaviors where you can choose either the left or the right side, you will notice that you have a lot of these, like, preferences that really barely change. Right? You don't start, like, suddenly hugging somebody on the left side if you always do the right side. So these are very deeply ingrained behavioral preferences.

有种刻板印象认为富有创造力的艺术工作者更可能是左撇子。研究支持这个观点吗？

Now there's a stereotype that creative artistic people are more likely to be left handed. Is that borne out by the research?

不，并不支持。近年来的大规模严格心理学研究表明，若采用客观创造力测试，左右撇子之间不存在显著差异。既有极具创造力的左撇子，也有极度缺乏创造力的左撇子；右撇子群体同样存在这种两极分布。

No. It is not. So, if you look at, like, studies, scale, highly controlled psychological studies from the last couple of years, it is pretty clear that if objective tests of creativity are used, there are no significant differences between left and right handers. So there's very creative left handers, but there's also extremely uncreative left handers. And there's very uncreative right handers, but there's also very creative right handers.

真正存在显著差异的是人们对左撇子创造力的态度和信念。无论左右撇子都强烈认为左撇子更具创造力，这甚至影响职业选择——例如家长更常建议左撇子女童从事创意行业。这似乎源于过去十年媒体传播形成的刻板印象效应。

Where there is a a large and significant effect is in people's attitudes and beliefs towards the creativity of left handers. So both left handed people and right handed people strongly believe that left handed people are more creative. And this also affects job choices. So for example, parents, tell their kids more often to maybe go into a creative profession when they're left handed. So there seems to be some sort of, like, stereotype effect here based on what, for example, has been communicated in the media about left handedness in the past decade.

然而现代严格控制的心理学研究并不支持这种观点。

That is, however, not backed up by, yeah, modern, highly controlled psychological science.

现在你写到了左撇子运动员在体育运动中往往比右撇子更成功。这背后的原因是什么？

Now you've written about how left handed athletes tend to be more successful at their sports than right handedness. What's behind that?

这也相当有趣，因为这似乎是由于他们的稀有性带来的效应。并不是说左撇子运动员本身在体育方面有什么更高的能力。对于某些类型的运动，比如网球等球拍运动，以及拳击等格斗运动，左撇子具有优势，这种优势就是出其不意。因为大多数人训练时都是和右撇子一起练习，毕竟右撇子人数多得多。所以人们在参加拳击比赛或网球比赛时，都是针对右撇子对手做准备。

That's also quite interesting because it seems to be an effect of their rarity. So it's not like that left handed athletes per se have some, like, higher ability in in sports. For certain types of sports, such as racket sports, like like tennis, and, like, combat sports, like, for example, boxing, left handers have a advantage, and that advantage is surprise. Like, so most people, if they train, they train with right handed people just because they are much more right handed people. So this is what people are prepared if they go into, like, a boxing fight or a tennis match.

当遇到左撇子选手时，他们可能之前与左撇子交手过，但总体来说概率要低得多。所以他们对抗左撇子对手的训练经验远不如对抗右撇子对手，数据也证明了这一点。数据显示在这些运动中，左撇子选手更成功，至少存在一定程度的过度代表。比如职业拳击手中左撇子的比例就高于普通人群。当然，如果左撇子人数过多，这种优势就会消失，因为他们就会像右撇子一样常见。

And then if somebody comes up and they're left handed, they might have played against left hander or or fought against the left hander before, but in general, like, the probability is much lower. So it's unlikely they have as much training experience as, when fighting or playing a right handed opponent, and it shows. So there are data that show that, left handed people in these sports are more successful and at least to, like, a certain overrepresentation. So they're, for example, more left handers and professional boxers than in the general population. But, of course, the advantage would disappear at some point if there are too many left handers because then they're as counted as right handers.

但这并不意味着他们在体育方面普遍更强。只是这个体系因为他们的稀有性而给了他们优势。

But it doesn't mean they're, like, generally better at sports. It's just the the system basically gives them an advantage due to their rarity.

我们来谈谈神经多样性人群。他们比右撇子更可能是左撇子吗？如果是的话，为什么？

Let's talk for a minute about neurodivergent people. Are they more likely to be left handed than right handed, and if so, why?

这是个非常有趣的研究领域，因为答案是肯定的。比如针对自闭症谱系障碍人群的大规模元分析表明，谱系人群成为左撇子或混合利手的概率明显高于普通人群。但为什么神经多样性个体中这种现象更普遍？目前还不清楚。

That's a quite interesting area of research because the answer is yes. There have been large scale meta analyses, for example, on people in autism spectrum disorders. And people on the spectrum typically have a higher chance of being left handed, being mixed handed than the general population. And why this is more common in neuro neurodiverse individuals? It's not well understood.

我们知道存在某些与自闭症谱系和左撇子相关的重叠遗传通路，但这只是非常非常少量的变异。不过总体发现相当可靠，效应量很大。我们正在研究中试图理解其中的原因。

So we know there's certain genetic pathways that that are overlapping between being on the spectrum ahead of us, but this is just a really, really tiny amount of variants. But the general finding is quite strong, so the effects are quite large. And we're trying to understand why in research.

是什么让你对这类研究产生兴趣的？你是左撇子还是右撇子？

What got you interested in this line of research, and are you a lefty or a righty?

我是右撇子，完全不是左撇子，可以说是百分之百的右撇子。我总体上对大脑如何产生行为非常感兴趣，而且我觉得这些进化过程中非常古老的结构组织原则极其迷人，比如所有大脑都有两半，对吧？

I'm right handed. I'm not left handed at all. I'm really like a 100% right hander. So I'm generally really interested in how the brain generates behavior, and I find it extremely fascinating that these evolutionary, very old structural organization principles, like all brains have two halves. Right?

如果你观察人类大脑，这是它最显著的视觉特征。对吧？它有两半。为什么会有两半呢？对吧？

That's the if you look at the human brain, it's the most striking visual, thing about it. Right? It has two halves. Why does it have two halves? Right?

因此，理解这一点以及它如何影响心理学和我们的日常生活、日常行为，是我一直觉得非常迷人的事情，因为这些是非常基础的结构，但它们至今仍在影响着我们。例如，如果你看人们在社交媒体上自拍，有一个非常强烈的效应是人们会先展示左脸颊，研究表明人们也认为展示左脸颊的人看起来情感上更温暖、更积极。所以人们会自然而然地，无需在认知上反思背后的心理科学，就采取不对称的姿势让别人更喜欢他们的照片。这不是他们刻意为之的行为，而是根深蒂固的，基于非常古老的神经科学过程。

So in understanding this and understanding how this affects psychology and how this affects our everyday lives, our everyday behavior is something I always felt incredibly fascinating because these are, like, very outstructural things, but they're still affecting us to the very day. So for example, if you look at people doing selfies for social media, there's a very strong effect that people would put their left cheek first, and research has shown that people also find quarters of people that show their left cheek in front, more emotionally warm, more emotionally positive. So people, like, naturally, without this cognitively reflecting on the psychological science behind this, go into an asymmetric posture to, have other people like their pictures more. And it's not something where they're like, oh, I do this now. This is something that's very deeply ingrained, and it's based on very old, neuroscientific processes.

我觉得这非常迷人。是的。

I find that very, fascinating. Yeah.

我读到过左撇子在心理学和大脑研究中经常代表性不足，而且他们经常被排除在研究之外。为什么会这样，这是个问题吗？

Now I've read that left handed people are often underrepresented in psychological and brain research and and that they're often screened out of research studies. Why does that happen, and is that a problem?

确实如此，而且这是个问题。之所以会这样，是因为心理学研究者长期以来认为左撇子可能会给数据带来噪音。他们让数据分析变得更复杂。让我解释一下为什么。例如，如果你进行一项关于语言心理学的研究，并使用MRI扫描仪观察人们在语言任务中的大脑激活情况。

That happens, and it is a problem. So the reason why that happens is that, researchers in psychology for a long time thought that left handers may introduce noise into the data. They make it more complicated to analyze the data. Let me explain why. So, for example, if you do a study on the psychology of language and you use an MRI scanner to look at the brain activation of people during a language task.

因此，如果你仅观察右撇子，你会发现约95%至100%的人在语言任务中表现出左脑半球激活，几乎所有人都是如此。而观察左撇子时，这种左脑激活仅出现在75%的左撇子中。另外25%的人会显示出异常的右脑半球激活。这只是正常的多样性表现。你看，人类大脑就是这样组织的。

So if you look only at right handed people, you would see a left hemispheric activation during language task in about ninety five to one hundred percent of people, so almost everyone. So if you now look at left handed people, you will find this left sided activation of the brain in only seventy five percent of left handers. Twenty five of them would show an unusual right hemispheric activation. This is just normal diversity. You know, this is how how human brains are organized.

这并没有什么不好或错误之处。但如果你现在进行一项心理学实验，进行人口抽样，其中10%是左撇子，90%是右撇子，你会发现少数人的结果模式与大脑激活是相反的——那些右脑激活的左撇子与其他人的模式不同。如果你对数据进行统计分析，主要关注所有参与者的平均值，你会发现整体效应会变得稍微不那么清晰，数据会显得更有噪声，因为有些人表现出相反的效应。但作为心理学家，我们当然应该拥抱这种多样性。为了做好科学研究，我们必须确保研究中涵盖人类大脑的所有方面。

There's nothing, like, bad or wrong with that. But if you now would do a psychological experiment and you just do a population sampling where 10% of people are left handed and ninety percent are right handed, you would have a few people that would show a reverse pattern of results and their brain activations, the left handers that have the right hemispheric activation, than the others. And if you now do a, statistical analysis of data that's very much focused on, the average across all participants, what you will find is then the the overall effect is a little bit, like, less clear, is a little bit no more noisy because you have some people that are having a reverse effect. But as psychologists, of course, we should embrace the diversity. We should make sure in order to do good science that we include all aspects of the human brain in our study.

因为如果我们系统性地排除某一群体，会发生什么？比如，如果计划进行某种临床干预，这些干预可能对左撇子并不理想，对吧？它们可能对左撇子效果不佳，甚至可能有害。

Because what happens if we, like, systematically exclude a group of people? What happens maybe if, for example, there are, like, clinical intervention planned on things like that, they might not be optimal for for left handed people. Right? They might not be great for left handed people. They might even be detrimental for left handed people.

这就是脑刺激技术面临的大问题。有些心理学家使用特定脑区的刺激作为治疗工具，比如在抑郁症治疗中认为这可能有效。但在这些临床研究中，刺激通常只针对大脑的一侧。

That's the big issue that like, brain stimulation techniques. Right? So there's psychologists who use, stimulation of certain brain areas as therapeutical tools. For example, the idea in in depression that it could be helpful. And, what happens there is that the stimulation in those studies, those clinical studies, is often on one side.

而我们的研究表明，这可能不是最优方案，因为如果人们的情感功能侧化是相反的（这在左撇子中更常见），他们可能无法从对大多数人有效的治疗中受益。因此，在基础心理学研究和临床心理学研究中，尤其是涉及单侧脑刺激时，必须纳入左撇子，并采用不同的数据分析方法。我们不应简单地把所有人混为一谈，而应更多地关注个体差异，并在统计中反映这一点。对吧？

But what our research would suggest is that may not be optimal, because if people have a switched lateralization of their emotion, and that's also more common left handers, they may not benefit from a treatment that is good for the majority of people. So what needs to be done is in both basic psychological research and clinical psychological research, especially if it comes to brain stimulation of one half of the brain, is that left handers should be included, and we just need a different way of analyzing the data. We shouldn't just, like, really mush all people together. But we should more look at, like, the individual variation and also reflect that in our statistics. Right?

所以可以说，比如75%的人显示左脑激活，其他人显示右脑激活，我们可以分别展示这些群体或类似方法。但我们绝对不应继续在心理学研究中排除左撇子。

So you can say, like, there are some people, like, 75% show it on on the left and the other on the right, and we, like, show these groups differentially or something like that. But we definitely should not continue to exclude left handed people in psychology.

最后总结一下，你现在在研究什么？还有哪些重大问题是你仍在试图解答的？

And just to wrap up, what are you working on now? What are the big questions you're still trying to answer?

我们目前的研究方向是试图理解人们训练非惯用手时会发生什么。我们开展了一些研究，志愿者会在一段时间内逐步训练他们的非惯用手，然后我们反复观察他们的大脑，试图找出哪些技能可以习得、哪些不能，以及背后的神经科学原理。我认为另一个非常有趣的领域是表观遗传学，即研究环境因素通过哪些分子过程影响用手习惯。实际上正在进行大量神经影像学研究，观察神经递质等如何在大脑扫描中呈现。总的来说，我们试图从生物学层面更深入地理解实际发生的机制。

What we're working on now is is we're trying to understand what happens when people are training their nondominant hand. So we have studies where people volunteer to train their nondominant hand a little bit over time, and then we repeatedly look at their brains and try to find out what can be learned, what cannot be learned, and what is the neuroscience behind that. And I think other research areas that are quite interesting, are topics like epigenetics, like what are the molecular processes over which these environmental factors are affecting handedness. There's a lot of neuroimaging actually going on, so what neurotransmitters and so on, are are mapping on brain scans and things like that. And I think in general, try to understand much more what has actually happened on a biological level.

好的，奥克伦伯格博士，感谢您参与对话。这次谈话非常有趣，谢谢。

Well, doctor Ochlenberg, I wanna thank you for joining me. It's been a very interesting conversation. Thanks.

谢谢你，金。很高兴能参加这次访谈。

Thank you, Kim. I was happy to be here.

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这里是美国心理学会，我是金·米尔斯。

For the American Psychological Association, I'm Kim Mills.