Interlanguage (IL) variability from a psycholinguistic perspective: A case study of Vietnamese ESL learners

This study investigates interlanguage (IL) variability from a psycholinguistic perspective in five Vietnamese learners of English as a second language. It focuses specifically on three morphological forms (present tense forms, past tense forms, and plural ‘-s’). A mixed methods approach was adopted, in which quantitative methods were used to analyse the learners’ written task performance under pressured and unpressured within-task planning conditions, and follow-up qualitative semi-structured interviews attempted to gain insight into the learners’ cognitive processes during their written task performance. Results of the written task performance revealed that the learners displayed two opposite (increasing and decreasing) patterns of IL variability in the morphological forms when they moved from time-pressured to unpressured task conditions. In addition, the learners also manifested different accuracy levels in each morpheme type. The interview data revealed that each individual learner demonstrated allocation of attentional resources to meaning and/or form in different ways in both pressured and unpressured within-task planning conditions. Moreover, the interview suggested that L1 transfer possibly contributed to the variations observed in the forms produced by the learners, alongside the limited working memory and attention capacity. The study suggests that an explanatory approach to understanding IL variability from the learner perspective has the potential to contribute to the field of second language acquisition. It also offers pedagogical implications, and suggestions for future larger-scale research projects that examine similar questions in a wider range of educational contexts.