【TED】意识是一种错觉？还是人类独有的奇妙感知？

P.S. had suffered a stroke that damaged the right side of her brain, leaving her unaware of everything on her left side. But though she could discern no difference between the houses, when researchers asked her which she would prefer to live in, she chose the house that wasn’t burning— not once, but again and again.

P.S.曾经中风，并导致损伤了大脑右部，这使她对在她左侧的东西没有意识。虽然她识别不出这两间房子的区别，当研究人员问她比较喜欢住哪一间的时候，她还是选了没有着火的那间。这不是一两次，而是一直这样。

P.S.’s brain was still processing information from her whole field of vision. She could see both images and tell the difference between them, she just didn’t know it. If someone threw a ball at her left side, she might duck. But she wouldn’t have any awareness of the ball, or any idea why she ducked.

P.S.的大脑仍然是根据她的整个视野来处理信息的。她是可以看见这两张图像并看出它们的区别的，她只是不知道。如果有人朝她的左边丢一个球，她也许会躲闪。但她并不会意识到有球向他飞来，也不明白为什么她会躲闪。

P.S.’s condition, known as hemispatial neglect, reveals an important distinction between the brain’s processing of information and our experience of that processing. That experience is what we call consciousness. We are conscious of both the external world and our internal selves— we are aware of an image in much the same way we are aware of ourselves looking at an image, or our inner thoughts and emotions.

P.S.的病症叫做半侧空间忽略症，它揭示了大脑处理信息和我们对于信息处理的经历的重要区别。这种经历我们称之为意识。我们对外在世界和自身内在有意识。我们意识到图像和我们意识到自己在看图像的方式差不多，这与意识到我们内在的思想感情，基本是一样的。

But where does consciousness come from? Scientists, theologians, and philosophers have been trying to get to the bottom of this question for centuries— without reaching any consensus.

但意识是从何而来呢？科学家，神学家和哲学家们几个世纪以来一直致力于解决这个问题，但都没有达成共识。

One recent theory is that consciousness is the brain’s imperfect picture of its own activity.

近来，有理论称意识是大脑对其自身活动的不完美写照。

To understand this theory, it helps to have a clear idea of one important way the brain processes information from our senses. Based on sensory input, it builds models, which are continuously updating, simplified descriptions of objects and events in the world. Everything we know is based on these models. They never capture every detail of the things they describe, just enough for the brain to determine appropriate responses.

理解这个理论之前，我们先来理清大脑是怎么根据我们的感知来处理信息的。大脑会根据我们的感官输入建立模型，这些模型不断地更新形成对于世间事物的简化描述。我们所知的每件事物都是基于这些模型。它们从不会抓住它所描述的事物的细节，但足以让大脑做出适当的反应。

For instance, one model built deep into the visual system codes white light as brightness without color. In reality, white light includes wavelengths that correspond to all the different colors we can see. Our perception of white light is wrong and oversimplified, but good enough for us to function. Likewise, the brain’s model of the physical body keeps track of the configuration of our limbs, but not of individual cells or even muscles, because that level of information isn’t needed to plan movement. If it didn’t have the model keeping track of the body’s size, shape, and how it is moving at any moment, we would quickly injure ourselves.

比如，视觉系统中的一个模型将白光编译为没有颜色的亮光。事实上，白光包含了所有不同颜色的可见光的波长。我们对于白光的感知是错的，而且是被过于简化的，但是足够我们用了。相同的，大脑中关于身体的模型会记录我们四肢的构型，但不会细致到记录单个细胞甚至肌肉，因为我们不需要这个层面的信息来活动。如果大脑没有一个追踪身体尺寸，形状以及动作的模型，我们很快就会伤到自己。

The brain also needs models of itself. For example, the brain has the ability to pay attention to specific objects and events. It also controls that focus, shifting it from one thing to another, internal and external, according to our needs. Without the ability to direct our focus, we wouldn’t be able to assess threats, finish a meal, or function at all. To control focus effectively, the brain has to construct a model of its own attention.

大脑也需要关于它自己的模型。例如，大脑有注意具体事物的能力。它还会根据我们的需要来控制这种专注，从一个东西转移到另外一个，从内在到外在。没有了转移注意的能力，我们就完全无法评定危险，无法吃饭，无法活动。为了有效控制注意力，大脑需要建立一个注意力模型。

With 86 billion neurons constantly interacting with each other, there’s no way the brain’s model of its own information processing can be perfectly self-descriptive. But like the model of the body, or our conception of white light, it doesn’t have to be. Our certainty that we have a metaphysical, subjective experience may come from one of the brain’s models, a cut-corner description of what it means to process information in a focused and deep manner.

大脑中有860亿个神经元持续交互，大脑信息处理的模型无法完美地记录描述自身的所有细节。但就像身体的模型一样，或者是我们对于白光的概念，这个模型并不需要是面面俱到的。我们确信我们有形而上学的主观体验，可能是因为某一个大脑模型。这个模型简易地描述了以集中而深入的方式处理信息的意义。

Scientists have already begun trying to figure out how the brain creates that self model. MRI studies are a promising avenue for pinpointing the networks involved. These studies compare patterns of neural activation when someone is and isn’t conscious of a sensory stimulus, like an image.

科学家们已在尝试研究大脑如何创造自我模型。核磁共振可以帮助我们查明关联的网络。这些研究对比当人是否意识到感官刺激时（比如图像）不同的神经活跃模式。

The results show that the areas needed for visual processing are activated whether or not the participant is aware of the image, but a whole additional network lights up only when they are conscious of seeing the image. Patients with hemispatial neglect, like P.S., typically have damage to one particular part of this network. More extensive damage to the network can sometimes lead to a vegetative state, with no sign of consciousness.

结果表明，不论试验人员是否意识到图片，大脑中视觉处理的区域都会被激活。但只有当他们有意识地看图像时，其他的网络才会全部活跃。患有半侧空间忽略症的病人，比如P.S.，通常是在这个网络的特定部位受损。对这一网络更严重的损伤可能会造成植物状态，使人完全失去意识。

Evidence like this brings us closer to understanding how consciousness is built into the brain, but there’s still much more to learn. For instance, the way neurons in the networks related to consciousness compute specific pieces of information is outside the scope of our current technology. As we approach questions of consciousness with science, we’ll open new lines of inquiry into human identity.

类似这样的证据让我们进一步明白意识是怎样建立在大脑中的。但还有更多有待学习。比如，我们目前的技术无法知晓在这一网络中和意识有关的神经元是如何计算具体某段信息的。随着我们利用科学解决意识的问题，我们将会开启关于人类特性的新探究。

来源：TED演讲

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