Mean Length of Utterance (MLU) is used as which type of measure in language assessment?

Mean Length of Utterance (MLU) is used as which type of measure in language assessment?

• A. A measure of vocabulary breadth.
• B. A predictor of processing speed.
• C. A metric for syntactic complexity derived from child speech samples; higher MLU indicates more complex syntax.
• D. A score of pragmatics use in conversation.

Answer: (C)

Mean Length of Utterance focuses on how complex a child’s sentences are. It’s calculated from a sample of child speech by counting morphemes (the smallest meaningful units, like walk, walked, walking, dog, dogs) and dividing by the number of utterances. This yields the average number of morphemes per utterance, which grows as children acquire more complex syntax and grammatical markings. In other words, a higher MLU reflects more elaborate sentence structure, longer phrases, and more advanced grammar. This measure is not about how many different words a child uses (vocabulary breadth), which would be a lexical quantity rather than syntactic structure. It also isn’t a direct measure of processing speed, since it looks at produced complexity rather than how quickly the child processes language. Nor is it about pragmatics—how language is used in social interaction. So a metric derived from child speech samples that captures syntactic complexity best matches what MLU assesses.

Mean Length of Utterance focuses on how complex a child’s sentences are. It’s calculated from a sample of child speech by counting morphemes (the smallest meaningful units, like walk, walked, walking, dog, dogs) and dividing by the number of utterances. This yields the average number of morphemes per utterance, which grows as children acquire more complex syntax and grammatical markings. In other words, a higher MLU reflects more elaborate sentence structure, longer phrases, and more advanced grammar.

This measure is not about how many different words a child uses (vocabulary breadth), which would be a lexical quantity rather than syntactic structure. It also isn’t a direct measure of processing speed, since it looks at produced complexity rather than how quickly the child processes language. Nor is it about pragmatics—how language is used in social interaction. So a metric derived from child speech samples that captures syntactic complexity best matches what MLU assesses.