It analyses the processes that make it possible to form a correct sentence out of vocabulary and grammatical structures. This process is called codification. Psycholinguistics also studies the factors that account for decodification, i.e., the psychological structures that allow us to understand utterances, words, sentences, texts etc.
To give an example, one field of research deals with questions like 'How do people learn a second language?' and 'How do children learn their native language?'. According to Noam Chomsky and his supporters, humans have an innate Universal Grammar (i.e., an abstract concept containing the grammatical rules of all world languages). Opponents of this view claim that language is learned only through social contact. However, it is scientifically proven that every healthy human being has the innate ability to learn many languages, as many as one is exposed to for a long enough period of time. This period of time lengthens considerably after the onset of puberty, so that children can learn any language fairly rapidly wheareas adults may require years to learn a second or third language. It also seems to be the case that the more languages one knows, the easier it is to learn more.
Another aspect of psycholinguistics involves studying individual use of language to understand the mental processes of the individual, a potentially useful tool for psychologists.