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人们是否已经揭开了意识之谜?

更新时间:2019/5/25 8:21:28 来源:纽约时报中文网 作者:佚名

Are we close to solving the puzzle of consciousness?
人们是否已经揭开了意识之谜?

Can a lobster feel pain in the same way as you or I?

龙虾能像人类一样感知到疼痛吗?

We know that they have the same sensors – called nociceptors – that cause us to flinch or cry when we are hurt. And they certainly behave like they are sensing something unpleasant. When a chef places them in boiling water, for instance, they twitch their tails as if they are in agony.

我们已经知道,龙虾和人类一样具有伤害感知系统。人类有这种特殊的“传感器”,因此在受伤时会畏惧退缩、或哭泣。人们观察龙虾后,发现这种动物也能够感觉不适。比如,一旦被厨师扔进了滚水中,龙虾就会蜷缩尾巴,好似痛苦不已。

But are they actually “aware” of the sensation? Or is that response merely a reflex?

然而,这当真是它们“感觉”到了吗?或仅仅只是条件反射呢?

When you or I perform an action, our minds are filled with a complex conscious experience. We can’t just assume that this is also true for other animals, however – particularly ones with such different brains from our own. It’s perfectly feasible – some scientists would even argue that it’s likely – that a creature like a lobster lacks any kind of internal experience, compared to the rich world inside our head.

人类一个简单的动作,背后是大脑中一系列复杂的意识经验。我们不能假设其他动物也会有这样的意识——尤其是大脑结构和人类大不相同的动物。但也不无可能,有些科学家甚至认为,连龙虾这种和没有任何内部经验的物种,也许都能产生意识。

“With a dog, who behaves quite a lot like us, who is in a body which is not too different from ours, and who has a brain that is not too different from ours, it’s much more plausible that it sees things and hears things very much like we do, than to say that it is completely ‘dark inside’, so to speak,” says Giulio Tononi, a neuroscientist at the University of Wisconsin-Madison. “But when it comes down to a lobster, all bets are off.”

威斯康辛麦迪逊大学(University of Wisconsin-Madison)的神经科学家托诺尼(Giulio Tononi)说:“比如说狗,行为方式更接近人类,身体结构也与人类更加相像。狗与人类的大脑结构也差得不远,因此犬类也有内部经验,它们看东西、听声音的方式和人类是一样的,也就合乎情理。但要说龙虾也能这样,就很难让人信服。”

The question of whether other brains – quite alien to our own – are capable of awareness, is just one of the many conundrums that arise when scientists start thinking about consciousness. When does an awareness of our own being first emerge in the brain? Why does it feel the way it does? And will computers ever be able to achieve the same internal life?

意识研究的众多难题之中,就有这么一项:大脑构造如果和人类的大不一样,是否还能够产生意识?其它的难题还包括,人类大脑中的意识是从什么时候开始产生的?为什么会产生这样的意识?有朝一日,人工智能是否能实现这样的感知?

Tononi may have a solution to these puzzles. His "integrated information theory" is one of the most exciting theories of consciousness to have emerged over the last few years, and although it is not yet proven, it provides some testable hypotheses that may soon give a definitive answer.

托诺尼或许能解开这些谜题。他提出的“整合信息理论”是近几年来最激动人心的意识理论之一。虽然该理论目前尚未被证实,但是其中一些假说,是能够用实验验证的。我们很快就能知道该理论是否正确。

Tononi says his fascination arose as a teenager with a “typically adolescent” preoccupation with ethics and philosophy. “I realised that knowing what consciousness is and how it came about is crucial to understanding our place in the universe and what we do with our lives,” he says.

托诺尼表示,早在青少年时代,他便“以青少年的专注”专攻伦理和哲学。他说:“那时我意识到,弄清楚什么是意识、知道意识是怎样形成的,是我们了解宇宙中人类的地位、知道如何对待自身生命的关键。”

At that age, he did not know the best path to follow to pursue those questions – Would it be mathematics? Or philosophy? – but he eventually settled on medicine. And the clinical experience helped to fertilise his young mind. “There is really something special about having a direct exposure to neurological cases and psychotic cases,” he says. “It really forces you to face directly what happens to patients when they lose consciousness or lose the components of consciousness in ways that are really difficult to imagine if you didn’t see that it actually happens.”

那时,他还不知道该选择什么样的道路来追寻这些问题的答案,是该选择数学吗?还是哲学?最终,他选择的是医学。临床经验的积累使他迅速成熟起来。他说:“获得第一手的神经学和精神病学案例,是一种很特殊的体验。我必须要直面失智或半失智的病人,看看他们那时候的状态。如果不是亲眼所见,是很难想象出来的。”

In his published research, however, he built his reputation with some pioneering work on sleep – a less controversial field. “At that time you couldn’t even talk about consciousness,” he says. But he kept on mulling over the question, and in 2004, he published his first description of his theory, which he has subsequently expanded and developed.

过去,托诺尼发表的研究成果中,广为认可的反而是在睡眠领域,内容更具开创性,这一领域内的争议也更小。他说:“当时,人们几乎不讨论意识。”即便如此,他也没放弃对意识问题的思考,终于在2004年,托诺尼发表了意识理论的第一篇文章。后续不断扩展和完善了这一理论。

It begins with a set of axioms that define what consciousness actually is. Tononi proposes that any conscious experience needs to be structured, for instance – if you look at the space around you, you can distinguish the position of objects relative to each other. It’s also specific and "differentiated" – each experience will be different depending on the particular circumstances, meaning there are a huge number of possible experiences. And it is integrated. If you look at a red book on a table, its shape and colour and location – although initially processed separately in the brain – are all held together at once in a single conscious experience. We even combine information from many different senses – what Virginia Woolf described as the “incessant shower of innumerable atoms” – into a single sense of the here and now.

文章开头是一组广为认可的公理,给意识下了定义。托诺尼提出,意识经验是需要精心安排的。打个比方,一个人环顾四周,会对周围物体之间的相对坐标有所了解。意识经验也是一个具体的概念,个体之间也“有所区别”。根据状况的不同,会有不同的意识经验产生。也就是说,意识经验有许许多多种。除此之外,意识经验具有集成性。当人们看到桌子上的一本红书时,虽然刚开始,我们会将其外形、颜色、所在位置分开处理,但是在同一个经验中,这几项属性最后也会被集成、整合到一起。大脑也会通过其他的感官整理信息,就像伍尔芙(Virginia Woolf)所言“[这些印象]像无数原子一样,从四面八方纷至沓来”,而大脑会将之整合到同一个时间和地点之中。

From these axioms, Tononi proposes that we can identify a person’s (or an animal’s, or even a computer’s) consciousness from the level of “information integration” that is possible in the brain (or CPU). According to his theory, the more information that is shared and processed between many different components to contribute to that single experience, then the higher the level of consciousness.

根据这些公理,托诺尼提出,我们能够从“信息整合”的水平上识别出一个人(或动物、人工智能)的意识,意识很可能就藏在大脑(或电脑的CPU)里。他的理论认为,单一经验中所需要感官共享和处理的信息越多,意识的水平就相对越高。

Perhaps the best way to understand what this means in practice is to compare the brain’s visual system to a digital camera. A camera captures the light hitting each pixel of the image sensor – which is clearly a huge amount of total information. But the pixels are not “talking” to each other or sharing information: each one is independently recording a tiny part of the scene. And without that integration, it can’t have a rich conscious experience.

要理解托诺尼理论的实际意义,我们可以把大脑的视觉系统类比成数码相机。相机能够以像素为单位,捕获照射到图像传感器上的光——捕获的总信息量显然是巨大的。而像素之间不能够互相“交流”、也不能共享信息:每一个像素负责独立记录场景中某一小部分的信息。如果相机没有集成功能,那么就无法获得完整的照片。

Like the digital camera, the human retina contains many sensors that initially capture small elements of the scene. But that data is then shared and processed across many different brain regions. Some areas will be working on the colours, adapting the raw data to make sense of the light levels so that we can still recognise colours even in very different conditions. Others examine the contours, which might involve guessing the parts of an object are obscured – if a coffee cup is in front of part of the book, for instance – so you still get a sense of the overall shape. Those regions will then share that information, passing it further up the hierarchy to combine the different elements – and out pops the conscious experience of all that is in front of us.

和相机一样,人类视网膜上有许多传感器,能够单独捕获场景中的某一微小元素。随后,大脑中的其他部分会收到这一共享信息,并且开始处理。大脑中,有的部分是负责处理色彩的,能够从原始数据中提取出光照水平。如此一来,在不同光源之下,我们就都能辨别各种颜色。还有的部分会检查物体形状,或许还能够推测出画面中被遮挡的部分——假设有一本书,前面被咖啡杯所遮挡,大脑还是能推断出书的整体形状。随后,大脑的这两部分会将处理后的信息进行整合,再进一步传递到大脑的其他部分,以便与其他信息整合。最后就成了我们的意识体验。

The same goes for our memories. Unlike a digital camera’s library of photos, we don’t store each experience separately. They are combined and cross-linked to form a meaningful narrative. Every time we experience something new, it is integrated with that previous information. It is the reason that the taste of a single madeleine can trigger a memory from our distant childhood – and it is all part of our conscious experience.

记忆的形成也是这样。和相机里存储的照片不同,记忆中的意识体验是相互联系的。不同意识体验之间的组合和关联,形成了各种有意义的故事。人们做了一件事情,就会将其和先前的经历联系在一起。这也就是为什么吃一个玛德琳蛋糕可能会勾起我们的童年回忆,因为意识体验是相互联系的。

At least, that’s the theory – and it’s compatible with many observations and experiments across medicine.

至少理论上来说是这样,许多医学观察和实验结果也不与之相悖。

One study, published in 2015, examined the brains of participants under various forms of anaesthesia – including propofol and xenon. To get an idea of the brain’s capacity to integrate information, the team applied a magnetic field above the scalp to stimulate a small area of the cortex underneath – a standard non-invasive technique known as Transcranial Magnetic Stimulation (TMS). When awake, you would observe a complex ripple of activity as the brain responds to the TMS, with many different regions responding, which Tononi takes to be a sign of information integration between the different groups of neurons.

2015年发表的一项研究,对异丙酚麻醉和氙气麻醉后的人类大脑进行了检查。为了验证大脑的信息整合功能,研究小组在参与者的头皮上方设置了一个磁场,以刺激大脑皮层的特定区域。这种无创技术叫做经颅磁刺激技术(Transcranial Magnetic Stimulation, TMS)。测试者意识清醒时,他们大脑的不同区域都会对TMS做出响应,产生一系列复杂的波动。托诺尼认为,这就是不同神经元之间进行信息集合的标志。

But the brains of the people under propofol and xenon did not show that response – the brainwaves generated were much simpler in form compared to the hubbub of activity in the awake brain.  By altering the levels of important neurotransmitters, the drugs appeared to have “broken down” the brain’s information integration – and this corresponded to the participants’ complete lack of awareness during the experiment. Their inner experience had faded to black.

在进行异丙酚和氙气麻醉后,测试者的大脑则不会对TMS产生任何反应——相比意识清醒时,此时的脑波形式更加简单。这两者能够改变大脑的神经递质水平,“破坏”大脑的信息整合功能——这一结果,恰好与实验参与者的完全昏迷相对应。彼时,他们的内在经验是完全空白的。

Drug-induced fantasies

药物致幻

As a further comparison, the team also looked at participants under ketamine. Although the drug renders you unresponsive to the outside world – meaning that it is also used as an anaesthetic – the patients frequently report wild dreams, as opposed to the pure “blank” experienced under propofol or xenon. Sure enough, Tononi’s team found that the responses to the TMS were far more complex than those under the other anaesthetics, reflecting their altered state of consciousness. They were disconnected from the outside world, but their minds were still very much turned on during their drug-induced fantasies.

为了进一步对比,还设置了一个实验组,是使用了氯胺酮麻醉的。人们在使用这种药物后不会对外界做出任何反应——因此它也是麻醉剂的一种。与异丙酚、氙气麻醉后完全空白的内在经验相反,许多患者表示,氯胺酮麻醉后会做很多不切实际的梦。托诺尼的团队也发现,这一组实验人员的大脑对于TMS的反应相比先前的麻醉组更加复杂,这就说明他们的意识状态发生了改变。虽然,氯胺酮也能切断个体和外界之间的关联,但个体的意识并没有归于空白,还徜徉在各种幻想出来的梦境之间。

Tononi has found similar results when examining different sleep stages. During non-REM sleep – in which dreams are rarer – the responses to TMS were less complex; but during REM sleep, which frequently coincides with dream consciousness, the information integration appeared to be higher.

在研究了睡眠的各个阶段时,托诺尼也发现了类似的结果。人们在在非快速眼动睡眠(non-REM;浅层睡眠)期间的梦少——对应TMS相对简单;REM睡眠(深层睡眠)期间经常会出现梦中意识,此时大脑的信息整合水平更高。

He emphasises that this isn’t “proof” that his theory is correct, but it shows that he could be working on the right lines. “Let’s say that if we had obtained the opposite result, we would have been in trouble.”

托诺尼说,实验并没有“证明”他的理论,但让他知道工作方向是正确的。“如果实验结果和理论相左,就真的麻烦了。”

Tononi’s theory also chimes with the experiences of people with various forms of brain damage. The cerebellum, for instance, is the walnut-shaped, pinkish-grey mass at the base of the brain and its prime responsibility is coordinating our movements. It contains four times as many neurons as the cortex, the bark-like outer layer of the brain – around half the total number of neurons in the whole brain. Yet some people lack a cerebellum (either because they were born without it, or they lost it through brain damage) and they are still capable of conscious perception, leading a relatively long and “normal” life without any loss of awareness.

托诺尼的理论也符合各种脑损伤患者的实际情况。小脑位于脑的底部,呈粉灰色核桃状,其主要功能是协调运动。小脑中的神经元数量是大脑皮层(大脑表面的树皮状组织)的四倍,占到了整个大脑神经元数量的一半。有人没有小脑(天生没有小脑,也有的是因脑损伤而切除),但还是能够进行感知。这部分人的生活“正常”,长寿,也不曾有意识空白。

These cases wouldn’t make sense if you just consider the sheer number of neurons to be important for the creation of conscious experience. In line with Tononi’s theory, however, the cerebellum’s processing mostly happens locally rather than exchanging and integrating signals, meaning it would have a minimum role in awareness.

如果认为意识经验仅和神经元数量有关,那这些案例是完全没有意义的。从托诺尼的理论来看,小脑主要负责内部的信息处理,信息的交互和集合较少,也就是说在意识的产生过程中作用较小。

Measures of the brain’s responses to the TMS also seem to predict the consciousness of patients in a non-communicative and vegetative state – a finding with potentially profound clinical applications.

测试大脑的TMS反应,也能够检测意识状态,帮助无法交流的患者和植物人——这一发现对于临床医学有着潜在的深远影响。

Great claims require great evidence, of course – and few scientific questions are more profound than the mystery of consciousness.

诚然,大胆的假说需要确凿的验证——科学界鲜有比意识之谜更深刻的问题了。

Tononi’s methods so far only offer a very crude “proxy” of the brain’s information integration – and to really prove his theory’s worth, more sophisticated tools will be required that can precisely measure processing in any kind of brain.

托诺尼目前的验证方法,只是提供了验证大脑信息整合作用的一个“测算替代物”。要真正证明该理论的价值,还需更加成熟的工具,能够以更加精确的方式、推算出大脑的各种信息处理过程。

Daniel Toker, a neuroscientist at the University of California Berkeley, says the idea that information integration is necessary for consciousness is very “intuitive” to other scientists, but much more evidence is required. “The broader perspective in the field is that it is an interesting idea, but pretty much completely untested,” he says.

加州大学伯克利分校(University of California Berkeley)的神经科学家托克(Daniel Toker)表示,信息整合是意识不可或缺的过程。对很多科学家来说这是“显而易见”的,但目前的凭据还不够充足。他说:“领域中有一个更广为认同的观点,即这个想法挺有趣的,只是完全没有被验证过。”

It all comes down to mathematics. Using previous techniques, the time taken to measure information integration across a network increases “super exponentially” with the number of nodes you are considering – meaning that, even with the best technology, the computation could last longer than the lifespan of the universe. But Toker has recently proposed an ingenious shortcut for these calculations that may bring that down to a couple of minutes, which he has tested with measurements from a couple of macaques. This could be one first step to putting the theory on a much firmer experimental footing. “We’re really in the early stages of all this,” says Toker.

归根溯源,还是数字计算的问题。使用先前技术时,如果要将神经网络中节点的数量考虑在内,计算单一神经网络中信息整合所耗费的时间就呈“指数”增长。也就是说,即使采用最尖端的科技,计算时间也是成倍于宇宙存在时间的。然而,托克近期发现了一条捷径,能够在几分钟之内获取计算结果。他已经在一批猕猴身上测试过了。这一发现,或能夯实托诺尼的理论,为其实验基础打下坚实的第一步。托克说:“我们真的刚刚起步。”

Only then can we begin to answer the really big questions – such as comparing the consciousness of different types of brain. Even if Tononi’s theory doesn’t prove to be true, however, Toker thinks it’s helped to push other neuroscientists to think more mathematically about the question of consciousness – which could inspire future theories.

在此之后,人们才得以慢慢回答一些真正重要的问题,比如,比较不同结构的大脑。托克认为,即使托诺尼的理论最后没有被证实,也至少推动了其他神经科学家的思考,让他们得以用更加数学的角度去看待意识的问题——或许对未来新理论的诞生有所帮助。

And should information integration theory be right, it would be truly game changing – with implications far beyond neuroscience and medicine. Proof of consciousness in a creature, such as a lobster, could transform the fight for animal rights, for instance.

如果整合信息理论最后被证实了,很多事情会随之改变。这一理论能够影响的,远不止神经科学界和医学界。比如,如果能证实龙虾等生物确实存在意识,将对动物权利保护有变革性的影响。

It would also answer some long-standing questions about artificial intelligence. Tononi argues that the basic architecture of the computers we have today – made from networks of transistors – preclude the necessary level of information integration that is necessary for consciousness. So even if they can be programmed to behave like a human, they would never have our rich internal life.

该理论还能够解答长期以来人们对于人工智能的困惑。在托诺尼看来,如今的计算机基本构架(晶体管网络),构不成信息集成的产生水平,更不用说产生意识了。因此,即使程序设定人工智能可以像人类,也绝对不可能有像我们那样丰富的内在世界。

“There is a sense, according to some, that sooner rather than later computers may be cognitively as good as we are – not just in some tasks, such as playing Go, chess, or recognising faces, or driving cars, but in everything,” says Tononi. “But if integrated information theory is correct, computers could behave exactly like you and me – indeed you might [even] be able to have a conversation with them that is as rewarding, or more rewarding, than with you or me – and yet there would literally be nobody there.” Again, it comes down to that question of whether intelligent behaviour has to arise from consciousness – and Tononi’s theory would suggest it’s not.

托诺尼说:“有些人认为,电脑的认知水平很快能够在方方面面赶上人类,而不仅仅是在围棋、象棋,或是人脸识别、驾驶汽车方面。但是,如果整合信息理论是正确的,那么人工智能的行为能完全复刻人类,也许[甚至]可以与之进行交流。这或许收获颇丰,有可能比人类之间的对话收获还要多。但即便是这样,它们也并不是人。”这就又回到了人工智能是否会自发行动的问题,根据托诺尼的理论,答案是否定的。

He emphasises this is not just a question of computational power, or the kind of software that is used. “The physical architecture is always more or less the same, and that is always not at all conducive to consciousness.” So thankfully, the kind of moral dilemmas seen in series like Humans and Westworld may never become a reality.

他强调说,这不仅关乎计算能力或软件类型:“计算机的物理构架大同小异,任何构架都无法产生意识。”所以谢天谢地,《人类》和《西部世界》剧集中的道德困境永远不能成为现实。

It could even help us understand the ways we interact with each other. Thomas Malone, director of the Massachusetts Institute of Technology's Center for Collective Intelligence and author of the book Superminds, has recently applied the theory to teams of people – in the laboratory, and in real-world, including the editors of Wikipedia entries. He has shown that the estimates of the integrated information shared by the team members could predict group performance on the various tasks. Although the concept of “group consciousness” may seem like a stretch, he thinks that Tononi’s theory might help us to understand how large bodies of people sometimes begin to think, feel, remember, decide, and react as one entity.

这一理论也能够让我们了解人类的互动模式。麻省理工学院集体智慧中心主任、《超级大脑》(Superminds)一书的作者马隆(Thomas Malone)近期将这一理论应用在了各种团队中——有实验室搭建的临时团队,也有现实生活中的团队,其中甚至有一组维基百科的编辑。实验证明,如果掌握了团队成员的整合信息,就能够预测出这个团队在各种任务中的发挥状态。现在看来“群体意识”这一概念还只是草图,但在马隆看来,托诺尼的理论有助于我们理解为什么有时候人们会像一个整体一样去想、去感知,甚至连记忆、决定和反应都是统一的。

He cautions this is still very much speculation: we first need to be sure that integrated information is a sign of consciousness in the individual. “But I do think it’s very intriguing to consider what this might mean for the possibility of groups to be conscious.”

他提醒道,如今尚只是一个大胆的猜测:第一,必须证明信息整合是个体具有意识的标志。“但是我认为,其中暗含群体意识存在的可能,也非常有意思。”

For now, we still can’t be certain if a lobster, computer or even a society is conscious or not, but in the future, Tononi’s theory may help us to understand ‘minds’ that are very alien to our own.

目前我们还不能知道龙虾和电脑是否能有意识,一个社会能否有群体意识。但是,在未来,托诺尼的理论或许能够帮我们理解完全不同于人类的“思想”。

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