INTRALINGUAL AND INTERLINGUAL INTERFERENCE: THE SOURCES OF THAI-LEARNERS’ ERRORS IN WRITING SELF-INTRODUCTION

Even though the study of language errors continued to grow in EFL learners' area, none of those studies addressed the source of language errors of Thai learners in writing. As a descriptive qualitative study, this research attempted to analyze the common types of grammatical errors and sources of errors made by Thai learners in writing self-introduction. The procedure of error analysis was adapted from Ellis and Barkhuizen (2005). The learners' self-introductions were collected through a writing prompt or blueprint as the instrument. The data were identified, analyzed based on Azar (1989), and the sources of error were classified by Brown (2007). The result showed there were 826 errors found in the learners' writing. The errors were caused by two main sources of error which are interlingual transfer and intralingual transfer. To conclude, grammar was found as a problem for Thai learners as EFL learners. So, the researcher suggests the teachers implement a suitable strategy to improve the students' writing and make a treatment called grammar clinic. Therefore, the result of this study can be used as a reference to conduct similar studies with different subjects or levels of the improvement of EFL learners' writing competence.