Task effects on phraseological complexity in learners’ written and oral production

The present study sought to advance the field of learner corpus research by investigating the role of task on phraseological complexity. To date, this role has been underin- vestigated, although the relevance of task complexity in second language acquisition is widely acknowledged. To this aim, a corpus of texts produced by second language learners from three proficiency levels – B1, B2 and C1 of the Common European Framework of Reference for Languages – based on four written and spoken tasks, and focused on an underrepresented L2 (Italian), was employed. Using structural equation models, a flexible and powerful tool for data analysis, the combined effects of task, proficiency and mode of production on phraseological di- versity and sophistication were analysed. Results supported the hypothesis that both phraseological diversity and sophistication increase with proficiency. Additionally, phraseological diversity increased in written productions through the mediating effect of task, and tended to decrease in more demanding tasks, where learners have more cognitively challenging demands.