The Neurobiology of Language Comprehension

The process of language comprehension consists of a number of distinct subprocesses which operate on different knowledge sources. The process from the input to the mental representation of the meaning that has been conveyed may be described as follows: as a first step peripheral input systems will have to process the auditory or visual language input, the phonological processing level will analyze the input and build up a phonological representation which allows access to the lexicon and the identification of given lexical entries. At the lexical level morphological aspects and semantic aspects become evident. When processing lexical elements in sentential context syntactic aspects such as the word’s syntactic category comes into play. Moreover, during sentence processing the system not only has access to those words that refer to the outside world, i.e., the content words, but access to function words also. These latter words indicate the grammatical relations holding between the content words and are therefore of major importance for a sentence’s interpretation. Grammatical relations may, depending on the language, also be marked by inflectional morphology. Function words and inflectional elements constitute the class of minor category items, the so-called closed class, whereas content words constitute the class of major category items, the so-called open class. The former class plus the information about a word’s syntactic category allow the building of a syntactic structure at the sentence level. The further integration of such sentence representations into world knowledge may be viewed as the process of ‘understanding’ in the most general use of this term. To achieve this the processing system furthermore identifies relations between different sentences in order to construct a propositional representation at a text or discourse level. All these processes must be completed with extreme speed in order to guarantee normal comprehension.