SLA Topics  SLA Bibliography  Vivian Cook 

MLU (Mean Length of Utterance) in Morphemes

  1. Record enough natural speech to yield at least one hundred consecutive utterances after stages 2 to 3

  2. Transcribe the speech.

  3. Eliminate:
    — all utterances where it is unclear what the child said.
    — exclamations, mm, oh, etc, except when they form the entire utterance
    — false starts, want - want drink

  4. Count the number of morphemes, both content and grammatical, counting as a single morpheme:
    — compound words, choo-choo, birthday etc
    — words with ‘ie/y’, mummy, doggie
    — irregular past tense, went
    but including as separate morphemes:
    · auxiliaries; will, , is,s, have, ve, etc
    · all inflected endings ‘-s’, ‘-ed’, etc

  5. Divide the total by the number of utterance to get the MLU in morphemes

L1 sources: Roger Brown, Paul Fletcher