Relationships of Linguistic Complexity and Accuracy to Functional Adequacy Across L2 English Speaking and Writing: Roles of L2 Proficiency and Task Type

Most research into the relationships of linguistic complexity and accuracy to functional adequacy has focused on either spoken or written mode. The current study extended previous studies by investigating these associations across both modalities and how the nature of these relationships was influenced by learners’ L2 proficiency and task type. To this end, 48 adult users of L2 English completed an advice task, a complaint task, a persuasive task, and a refusal task in speaking and writing modalities. Participants’ L2 proficiency was established by a cloze test. Each performance was rated for functional adequacy and coded for lexical complexity, syntactic complexity, and accuracy. Linear mixed-effects regression analyses revealed no relationship of linguistic complexity and accuracy to functional adequacy in speaking, while greater phrasal complexity and fewer errors contributed to higher functional adequacy in writing. L2 proficiency was found to influence the way in which phrasal complexity linked to functional adequacy in speaking and the relationships between accuracy and functional adequacy in both speaking and writing. An impact of task type was identified on how lexical sophistication and syntactic accuracy related to functional adequacy in the written mode, but no task effect was found for the spoken mode. Based on these findings, implications on L2 instruction across modalities, levels of proficiency, and task types were drawn.