top-down processing

in PSYCHOLINGUISTICS, COGNITIVE PSYCHOLOGY, and INFORMATION PROCESSING, a contrast is made between two different ways in which humans analyze and process language as party of comprehension and learning. One way, known as top-down processing, makes use of "higher level", nonsensory information to predict or interpret "lower level" information that is present in the data. The other way, bottom-up processing, makes use of the information present in the input to achieve higher level meaning. The meanings of these terms varies depending on the unit of analysis. For example, in word recognition, the higher level information is knowledge of permissible words as well as actual words of a language, while the lower level information is the actual phonetic input (or orthographic input in the case of written word recognition). In sentence comprehension or the interpretation of an UTTERANCE, the lower level information is words, while the higher level information includes knowledge of GRAMMAR, SEMANTICS, and PRAGMATICS. As applied to the full understanding of a novel, lower level information consists of words and sentences, while higher level information includes the reader's previously existing knowledge of the world, including cultural and moral values, SCRIPTs, SCHEMAs, and literary GENREs.

Jack C. Richards, Richard Schmidt., Longman Dictionary of Language Teaching & Applied Linguistics, p.567