mean length of utterance (MLU)

A measure introduced by the American psychologist Roger Brown (1925–1997) into LANGUAGE ACQUISITION studies in the 1960s, which computes the LENGTH of an UTTERANCE in terms of MORPHEMES. The technique is then used to show the increasing length of a child’s utterances over time, as a base-line for carrying out studies on the developmental complexity of SENTENCE STRUCTURE. The notion was introduced to get round the problem of correlating age with linguistic development.