Top down processing sensory (sight, smell, touch, taste, and sound) input into large chunks of infomation. In top down processing perceptions are formed based on our previous experiences beginning with the largest idea or concept and gradually working towards the finner details.
For example, it is easier to read messy handwriting in a sentence than trying to read one word because the sentence provides a context for processing the handwriting. See how you go from larger to smaller in the sentance. It might be very difficult to identify a single letter, but easier in the context of the whole sentence.
- The hmaun mnid uses top down prconiessg to read, as it does not read every leettr by ietslf, rthaer the wrod as a wlohe. As lnog as the fisrt and lsat ltreets are in the crceort plcae it dseon't maettr what oredr the lettres of a wrod are in. You can siltl raed it!
The human mind uses top down processing to read, as it does not read every letter by itself, rather the word as a whole. As long as the first and last letters are in the correct place it doesn't matter what order the letters of a word are in. You can still read it!...That is top down processing at work!