Collocation Use and L1 Raters’ Judgments of L2 Speech: Exploring the Role of Mutual Information

This study examined the relationship between collocation use (i.e., meaningful co-occurrences of multiple words) and first language (L1) raters’ intuitive judgments of second language (L2) speech. Speech samples were collected from 85 Japanese learners of English with varying L2 proficiency levels, who participated in a picture description task. Ten native English speakers rated the speech samples for global comprehensibility (the ease of understanding the speech) and lexical appropriateness (the adequacy and naturalness of word use in context). The samples were then analyzed using a range of lexical measures, focusing on the collocation (frequency, association), depth (abstractness), and breadth (frequency, range) aspects of L2 vocabulary use. Statistical analyses revealed that the L1 raters’ comprehensibility and lexical appropriateness scores were strongly influenced by the L2 speakers’ use of low-frequency collocations, particularly those containing infrequent, abstract, and complex words (i.e., mutual information). This finding suggests that incorporating such collocations into L2 production can significantly enhance the fluency and naturalness of speech, leading to more favorable evaluations from native speakers.