原文出处： https://explorable.com/top-down-vs-bottom-up-processing

Generally speaking, there are two approaches to understanding the process of perception. These are the top-down processing and the bottom-up processing. What differentiates one from the other? Let's find out.

通俗来讲，这里有两种方法来理解感知的过程。这就是从上到下（top-down processing）和从下到上（bottom-up processing）的处理过程。那么二者之间有什么区别呢？

Top-down processing is defined as the development of pattern recognition through the use of contextual information. For instance, you are presented with a paragraph written with difficult handwriting. It is easier to understand what the writer wants to convey if you read the whole paragraph rather than reading the words in separate terms. The brain may be able to perceive and understand the gist of the paragraph due to the context supplied by the surrounding words.

自上而下的处理过程被定义为：在模式识别的过程中使用了上下文信息。比如，当你看到了一张字迹潦草难以辨认的手写文本时，你可以利用整个文本来辅助你理解其中含义，而不是每个字单独辨认。正因为有了周围字体的上下文信息，大脑可以去感知和理解文本里的意思。

注：

这个比较好理解了，比如学书法时看的字帖，其中有些字单独看，很难明白其意思，但是如果连起来看，因为有先验知识的存在，就相对容易理解了。比如正好是一个成语，三个字认识，其中一个不认识，如果知道了这个成语，那这个不认识的古汉字，对你而言也是可以辨认理解的。

In the bottom-up processing approach, perception starts at the sensory input, the stimulus. Thus, perception can be described as data-driven. For example, there is a flower at the center of a person's field. The sight of the flower and all the information about the stimulus are carried from the retina to the visual cortex in the brain. The signal travels in one direction.

自下而上的处理可以理解为：将感应器结果作为输入，也就是激励。因此自下而上可以被描述为是数据驱动的。例如，在一个人的花园正中有一朵花儿，这个花儿的视觉和所有的激励信息都从视网膜上通过视神经传递到大脑，然后大脑分析后得到图像。这些信息的传递时单方向的。

注：

这个比较好理解了。