評論
打印
So why is it that we move the particular ways we do?
那我們?yōu)槭裁从眠@種特定的模式移動呢？
Well let's think about what really happens. Maybe we don't all quite move the same way.
來想想真實情況可能是什么。假如我們并不都用同一種模式移動。
Maybe there's variation in the population.
假如人群中有差異。
And maybe those who move better than others have got more chance of getting their children into the next generation.
而且假如那些比其他人移動得更好的個體有更多機會讓他們的子代進入下一代的群體里面。
So in evolutionary scales, movements get better.
那么在進化級別上，動作越來越優(yōu)化。
Perhaps in life, movements get better through learning.
另外，也許在一生當中，學(xué)習(xí)會讓動作更優(yōu)化。
So what is it about a movement which is good or bad?
那么，是什么決定了動作的好與壞呢？
Imagine I want to intercept this ball.
來想象我要截下這個球。
Here are two possible paths to that ball.
這里有兩種路徑來做到。
Well if I choose the left-hand path, I can work out the forces required in one of my muscles as a function of time.
假如我選了左手邊這條路徑，我可以算出某一塊肌肉需要施多大力，用關(guān)于時間的函數(shù)表示。
But there's noise added to this.
但是還有雜音附加在上面。
So what I actually get, based on this lovely, smooth, desired force, is a very noisy version.
所以根據(jù)這條美好、光滑、期望中的曲線，我事實上得到的是個雜音很大的版本。
So if I pick the same command through many times, I will get a different noisy version each time, because noise changes each time.
那如果我多次發(fā)布同樣的動作指令，每次會得到不同的含雜音的版本，因為每次雜音不一樣。
So what I can show you here is how the variability of the movement will evolve if I choose that way.
所以我現(xiàn)在在這兒展示的只是這個動作的可變性有多大，前提是如果我選這種方式的話。
If I choose a different way of moving -- on the right for example -- then I'll have a different command, different noise, playing through a noisy system, very complicated.
如果我選另一種方式--比如右邊這個--那我就會有不同的指令，不同的雜音，還要透過雜音系統(tǒng)，總之非常復(fù)雜。
All we can be sure of is the variability will be different.
我們唯一能確定的是，兩個方式的可變性會不同。
If I move in this particular way, I end up with a smaller variability across many movements.
要是我用這種方式運動的話，最后得到的可變性在很多種動作里面是最小的。
So if I have to choose between those two, I would choose the right one because it's less variable.
所以要是我在這兩者里面選其一，我就會選右邊那個，因為可變性更小。
