Language Comprehension; The nature of understanding

In understanding the language, there are four level of language processing. Those are:
1.    Perceptual  Level
At the perceptual level, we could describe your processing activities as a series of eye movements that are used to encode the constituent letters of words, including speech sound, written symbols, and signs.
2.    Lexical Level
At the lexical level, we use the identified letters to retrieve the lexical representation of a word from permanent memory. This representation will include the meaning of the word, its spelling, its pronunciation, its part of speech, and related characteristic. In short, the representation is what we know about a word.
3.    Sentential Level
We analyze the sentence structure of the ongoing linguistic message. In this case the sentence contains two clauses, and the subordinate clauses come first. We use working memory to store the contents of the first clause while we process the second, then form some unified representation of the entire sentence.
4.    Discourse Level
We identify the context preceding and following a sentence and integrate the sentence representation with that context.