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That information is available in the current shot, but there's another source of information not available on the current shot,
以上这些信息是实时获得的，但是另一个获得信息的渠道，不是实时获得的，
but only available by repeated experience in the game of tennis,
而是来自只有通过反复练习网球才得来的经验，
and that's that the ball doesn't bounce with equal probability over the court during the match.
经验告诉你，这个网球在比赛过程中，不会以均等的概率落在球场里。
If you're playing against a very good opponent,
如果你的对手水平很高，
they may distribute it in that green area, which is the prior distribution, making it hard for you to return.
可能会让球的落点分布在图上的绿色区域，也就是所谓的“先验分布”，这些位置很难接到球。
Now both these sources of information carry important information.
那么现在，两个信息源都包含重要的信息。
And what Bayes' rule says is that I should multiply the numbers on the red by the numbers on the green to get the numbers of the yellow, which have the ellipses, and that's my belief.
根据贝叶斯的理论，我们应该把红色区域和绿色区域的数据相乘得到椭圆形的黄色区域，这就是我们的置信值。
So it's the optimal way of combining information.
并且这是整合信息的最佳方案。
I wouldn't tell you all this if it wasn't that a few years ago,
几年前我们考察过，人们学习新动作新技巧的时候，
we showed this is exactly what people do when they learn new movement skills.
真的在遵循这样的模式，所以我刚才才举了这个例子。
And what it means is we really are Bayesian inference machines.
这说明我们实际上都是天生的贝叶斯推断器。
As we go around, we learn about statistics of the world and lay that down,
在成长的过程中，我们不但学会了并记下了生活中的统计数据，
but we also learn about how noisy our own sensory apparatus is, and then combine those in a real Bayesian way.
也掌握了我们自己感官的杂音可能有多大，然后我们用贝叶斯法来整合处理这些数据。
Now a key part to the Bayesian is this part of the formula.
那么贝叶斯公式里很关键的是这一项--预测。
And what this part really says is I have to predict the probability of different sensory feedbacks given my beliefs.
这一项的意思是我们需要预测在原有置信值条件下，不同感官回馈的概率。
So that really means I have to make predictions of the future.
也就是说我们要对未来的可能做出预测。
And I want to convince you the brain does make predictions of the sensory feedback it's going to get.
我现在要说服各位相信一点，那就是大脑的确在对未来可能的感官回馈做出预测。
And moreover, it profoundly changes your perceptions by what you do.
并且你本身做了什么动作在很大程度上影响了你感知到的东西。
And to do that, I'll tell you about how the brain deals with sensory input.
为了说明这点，我来解释我们的大脑如何处理感官输入。
So you send a command out, you get sensory feedback back, and that transformation is governed by the physics of your body and your sensory apparatus.
我们先送出一个指令，然后得到一个感官回馈输入回来，之间的转换过程是由身体和感觉器官的物理过程完成的。
