Interlingual and Intralingual Interference: Two Sources of Writing Errors of Thai EFL students


According to previous research studies, errors found in Thai EFL students’ writing are based on two sources: interlingual and intralingual interference. Errors can be based on three perspectives of interlingual interference (Kaweera, 2013). Those perspectives include lexical, syntactic, and discourse interference. Another source of errors is intralingual interference. According to Richards (1985), there are four types of intralingual interference including overgeneralization, ignorance of rule restrictions, incomplete application of rules, and false concepts hypothesis. The study of interlingual and intralingual interference is popular for Thai EFL researchers because it has been found for a long time that students always make a lot of errors when they write sentences, paragraphs, or even essays. Although it is not hard to find research studies based on this area, it is still difficult for both students and teachers to cope with this problem in the real situation. Therefore, it is currently found that Thai EFL researchers are interested in this issue, and they are trying to find the best solution to cope with this problem.

Interlingual Interference

In comparing interlingual and intralingual interference, interlingual interference is found to be the main source of errors (Phetdannuea & Ngonkum, 2016; Rattanadilok Na Phuket & Othman, 2015). This is because the native language plays a significant role in learning the target language. When Thai EFL students learn English language, they try to use the knowledge of their native language, which is Thai language, to help perform their writing tasks. To be specific, rules and structures of their native language are used by students when they find that the target language, which is English language, is difficult for them. This can be considered one of learning strategies that students use in order to learn the target language.

As mentioned in the previous section, there are three perspectives of interlingual interference including lexical, syntactic, and discourse interference (Kaweera, 2013). Firstly, lexical interference happens when students directly translate Thai words into English. Some words cannot be used in every context, but they do not consider this rule. Therefore, they make errors when writing some sentences. For example, students produce I play the internet instead of I surf the internet. Secondly, syntactic interference happens when students construct English sentences based on direct translation. In addition to literal translation from Thai to English, there are other types of errors caused by syntactic interference, such as agreement errors, run-on sentences, and so on (Phetdannuea & Ngonkum, 2016). Finally, discourse interference refers to an unclear topic sentence in a paragraph. Besides, incoherence is caused by discourse interference; that is, students have problems when expressing ideas in a paragraph.

In addition to learning strategies, the native language interference can occur due to other reasons. According to Rattanadilok Na Phuket and Bidin (2016), inadequate knowledge of the target language and attitude towards English are also the reasons of native language interference in EFL writing. Thai EFL teachers are aware of this problem, and they are trying to help minimize errors based on the reasons of native language interference. However, it is not easy to deal with this problem because students make errors in writing both inside and outside the classroom. In other words, due to the native language interference, Thai EFL students who become EFL writers can make errors in writing in the real situation. According to Kongkaew and Cedar (2018), EFL authors who work for the Tourism Authority of Thailand Website made errors in online English writing, and errors of omission were found to be the most frequent among different types of errors EFL authors made.

Intralingual Interference

According to Richards (1985), intralingual interference is considered another source of errors. It can happen when students know only some rules of the target language. As mentioned earlier, four types of intralingual interference consist of overgeneralization, ignorance of rule restrictions, incomplete application of rules, and false concepts hypothesis. Firstly, overgeneralization refers to the creation of deviant structures by students. For example, some students produce she can sings instead of she can sing. They produce this sentence based on knowledge of two regular structures. Secondly, ignorance of rule restrictions means that students make use of rules without considering its limitation. It happens when they have to use the rules that they have learned before in the new context. For example, students produce the man who I saw him instead of the man who I saw. Thirdly, incomplete application of rules refers to failing to learn some complex structures. In this case, students misuse some rules when they have to communicate. For example, when the teacher asks students “What was he saying?”, students answer he saying he would ask her instead of he is saying he would ask her. Finally, false concepts hypothesis means that students misunderstand the use of some forms. For example, students produce she was died yesterday because they think that was is used as the marker of the past tense.


Taking everything into consideration, research studies on the effects of interlingual and intralingual interference on Thai EFL students’ writing are needed because students always make errors when they perform writing tasks. In comparing to neighboring countries (e.g., Malaysia, Indonesia, Vietnam, and Singapore), Thai students underperform English writing skill (Waelateh, Boonsuk, Ambele, & Jeharsae, 2019). Consequently, Thai EFL teachers need to understand the reasons of interlingual and intralingual interference as they need to help students write accurately.


Kaweera, C. (2013). Writing error: A review of interlingual and intralingual interference in EFL context. English Language Teaching, 6(7), 9-18.

Kongkaew, S., & Cedar, P. (2018). An analysis of errors in online English writing made by Thai EFL authors. International Journal of Applied Linguistics and English Literature, 7(6), 86-96.

Phetdannuea, F., & Ngonkum, S. (2016). An analysis of interlingual errors and intralingual errors in Thai EFL students’ writing at Khon Kaen University. KKU Research Journal (Graduate Studies) Humanities and Social Sciences, 4(2), 35-51.

Rattanadilok Na Phuket, P., & Bidin, S. J. (2016). Native language interference in writing: A case study of Thai EFL learners. International Journal of Foreign Language Teaching and Research, 4(16), 25-36.

Rattanadilok Na Phuket, P., & Othman, N. B. (2015). Understanding EFL students’ errors in writing. Journal of Education and Practice, 6(32), 99-106.

Richards, J. C. (1985). The context of language teaching. Cambridge: Cambridge.

Waelateh, B., Boonsuk, Y., Ambele, E. A., & Jeharsae, F. (2019). An analysis of the written errors of Thai EFL students’ essay writing in English. Songklanakarin Journal of Social Sciences and Humanities, 25(3).