There are certain assumptions the visual system makes

视觉系统会做出一些假定
that aren't always right

但并不一定正确
and in fact,

而且事实上
in cases of visual illusions, can be wrong

在视觉错觉中这些假定就是错的
but will guide you

但却能指导你
to perceive the world in a correct and accurate way.

以恰当准确的方式来感知这个世界
So for example, there is binocular disparity.

例如我们有双眼视差
This is actually a sort of interesting one.

这其实是一个有趣的现象
This is the only depth cue that involves two eyes.

这是唯一关系到两只眼睛的深度线索
If I look at you pretty close,

如果我离你很近地看你
the image I get here and the image I get here are somewhat different while--

我的两只眼睛所看到的图像是不同的
or I have to focus my eyes together

或者我必须使双眼汇聚在同一点上