The Effect of Deliberate Learning of English Multiword Expressions on Low and High L2 Learners' Motivation Based on the L2MSS Model.

This article investigates the impact of deliberate learning of English multiword expressions (MWEs)—specifically idioms, binomials, and collocations—on the motivation of Iranian second language (L2) learners, using the L2 Motivational Self System (L2MSS) model. The study, conducted in two phases with low and upper-intermediate proficiency learners, found that MWE instruction significantly enhanced motivation across three L2MSS dimensions: the ideal L2 self, ought-to L2 self, and L2 learning experience. Notably, low-proficiency learners' motivation was primarily influenced by the ought-to L2 self (external expectations), while upper-intermediate learners were more motivated by the ideal L2 self (intrinsic aspirations). The findings suggest that integrating MWEs into language teaching can support both linguistic competence and learners' identity development, with pedagogical approaches tailored to proficiency-related motivational profiles.