Examining the Link between Thai L2 University Students' Vocabulary Size and Academic Vocabulary Depth

Authors

  • Pasara Namsaeng

    Department of Western Languages and Linguistics, Mahasarakham University, Maha Sarakham 44150, Thailand
  • Apisak Sukying

    Department of Western Languages and Linguistics, Mahasarakham University, Maha Sarakham 44150, Thailand
  • Pilanut Phusawisot

    Department of Western Languages and Linguistics, Mahasarakham University, Maha Sarakham 44150, Thailand

DOI:

https://doi.org/10.30564/fls.v7i12.11926
Received: 2 September 2025 | Revised: 24 September 2025 | Accepted: 29 September 2025 | Published Online: 5 November 2025

Abstract

This study examines the vocabulary size and academic vocabulary depth knowledge among Thai pre-service English teachers, aiming to elucidate the relationship between these dimensions, which are essential for effective teaching. A total of 288 participants, aged 18 to 22, from three universities in northeastern Thailand, were assessed using two primary instruments: the Vocabulary Size Test (VST) and the Academic Vocabulary Knowledge Scale (AVKS). The VST measures participants' receptive vocabulary size through multiple-choice questions, while the AVKS evaluates participants' depth of knowledge regarding 16 specific academic words. To assess the validity and reliability of the measurement tools, Rasch analysis was employed, emphasizing four core principles: unidimensionality, local independence, reliability, and model-data fit. The findings reveal that participants demonstrate a moderate average understanding of academic vocabulary, with significant variability in the depth of knowledge across different words. Correlation analysis reveals a weak positive relationship between vocabulary size and academic vocabulary depth, indicating that as vocabulary size increases, academic vocabulary knowledge tends to improve, albeit modestly. Despite these findings, the results highlight the need for improved vocabulary teaching strategies to fully develop both dimensions in pre-service teachers, which is crucial for success in the academic and professional aspects of English language learning. The study offers valuable insights and underscores the importance of integrating both vocabulary size and depth into language education curricula.

Keywords:

Academic Vocabulary Depth; Rasch Analysis; Thai Pre-service Teachers; Vocabulary Size

References

[1] Nation, I.S.P., 2022. Learning Vocabulary in Another Language, 3rd ed. Cambridge University Press: Cambridge, UK.

[2] Duran, D., Kääntä, L., 2023. Building word knowledge through integrated vocabulary explanations in ESL tutorials. Linguistics and Education. 75, 101182. DOI: https://doi.org/10.1016/j.linged.2023.101182

[3] Nontasee, W., Sukying, A., 2021. The learnability of word knowledge aspects in Thai EFL high school learners. Journal of Language and Linguistic Studies. 17(1), 34–55.

[4] Nontasee, W., Sukying, A., 2023. Multiple aspects of word knowledge in Thai EFL students: The hierarchical acquisition and relationships. GEMA Online Journal of Language Studies. 23(1). DOI: http://dx.doi.org/10.17576/gema-2023-2301-02

[5] Teng, M.F., Mizumoto, A., 2024. Validation of metacognitive knowledge in vocabulary learning and its predictive effects on incidental vocabulary learning from reading. International Review of Applied Linguistics in Language Teaching. 63(3), 1941–1972. DOI: https://doi.org/10.1515/iral-2023-0294

[6] Zhong, H.F., 2016. The relationship between receptive and productive vocabulary knowledge: a perspective from vocabulary use in sentence writing. The Language Learning Journal. 46(4), 357–370. DOI: https://doi.org/10.1080/09571736.2015.1127403

[7] Coxhead, A., Nation, P., Sim, D., 2015. Measuring the vocabulary size of native speakers of English in New Zealand secondary schools. New Zealand Journal of Educational Studies. 50(1), 121–135. DOI: https://doi.org/10.1007/s40841-015-0002-3

[8] Read, J., 2000. Assessing Vocabulary. Cambridge University Press: Cambridge, UK. DOI: https://doi.org/10.1017/CBO9780511732942

[9] Schmitt, N., 2014. Size and depth of vocabulary knowledge: What the research shows. Language Learning. 64(4), 913–951. DOI: https://doi.org/10.1111/lang.12077

[10] Anderson, R.C., Freebody, P., 1981. Vocabulary knowledge. In: Guthrie, John T., (Ed.). Comprehension and Teaching: Research Reviews. International Reading Association, Newark, DE, USA. pp. 77–117.

[11] Read, J., 2004. Research in teaching vocabulary. Annual Review of Applied Linguistics. 24, 146–161. DOI: https://doi.org/10.1017/S0267190504000078

[12] Sukying, A., 2018. Investigating receptive and productive affix knowledge in EFL learners. In: Hirsh, D. (Ed.). Explorations in Second Language Vocabulary Research. Peter Lang: Bern, Switzerland. pp. 183–218.

[13] Akbarian, I.H., 2010. The relationship between vocabulary size and depth for ESP/EAP learners. System. 38(3), 391–401. DOI: https://doi.org/10.1016/j.system.2010.06.013

[14] Janebi Enayat, M., Derakhshan, A., 2021. Vocabulary size and depth as predictors of second language speaking ability. System. 99, 102521. DOI: https://doi.org/10.1016/j.system.2021.102521

[15] Han, D., Qian, D.D., 2024. Evaluating the roles of breadth and depth of aural vocabulary knowledge in listening comprehension of EFL learners: An investigation applying auditory measures. System. 120, 103207. DOI: https://doi.org/10.1016/j.system.2023.103207

[16] Şen, Y., Kuleli, M., 2015. The effect of vocabulary size and vocabulary depth on reading in EFL context. Procedia-Social and Behavioral Sciences. 199, 555–562. DOI: https://doi.org/10.1016/j.sbspro.2015.07.546

[17] Edmonds, A., Clenton, J., Elmetaher, H., 2022. Exploring The Construct Validity Of Tests Used To Assess L2 Productive Vocabulary Knowledge. System. 108, 102855. DOI: https://doi.org/10.1016/j.system.2022.102855

[18] Malmström, H., Pecorari, D., Shaw, P., 2018. Words for what? Contrasting university students' receptive and productive academic vocabulary needs. English for Specific Purposes. 50, 28–39. DOI: https://doi.org/10.1016/j.esp.2017.11.002

[19] Sukying, A., 2020. Word Knowledge Through Morphological Awareness In EFL Learners. TESOL International Journal. 15(1), 74–85.

[20] Torabian, A.H., Maros, M., Subakir, M.Y.M., 2014. Lexical collocational knowledge of Iranian undergraduate learners: Implications for receptive & productive performance. Procedia-Social and Behavioral Sciences. 158, 343–350. DOI: https://doi.org/10.1016/j.sbspro.2014.12.098

[21] Nation, I., Beglar, D., 2007. A vocabulary size test. The Language Teacher. 31, 9–13.

[22] Read, J., 1998. Validating a test to measure depth of vocabulary knowledge. In: Kunnan, A.J. (Ed.). Validation in Language Assessment, 1st ed. Routledge: New York, NY, USA.

[23] Marzban, A., Hadipour, R., 2012. Depth versus breadth of vocabulary knowledge: Assessing their roles in Iranian intermediate EFL students' lexical inferencing success through reading. Procedia-Social and Behavioral Sciences. 46, 5296–5300. DOI: https://doi.org/10.1016/j.sbspro.2012.06.426

[24] Schmitt, N., Schmitt, D., Clapham, C., 2001. Developing and exploring the behaviour of two new versions of the Vocabulary Levels Test. Language Testing. 18(1), 55–88. DOI: https://doi.org/10.1177/026553220101800103

[25] Dabbagh, A., Janebi Enayat, M., 2019. The role of vocabulary breadth and depth in predicting second language descriptive writing performance. The Language Learning Journal. 47(5), 575–590. DOI: https://doi.org/10.1080/09571736.2017.1335765

[26] Wu, S., Quentin Dixon, L., Sun, H., et al., 2021. Breadth or depth: the role of vocabulary in Chinese English language beginning writers’ development. International Journal of Bilingual Education and Bilingualism. 24(9), 1356–1372. DOI: https://doi.org/10.1080/13670050.2019.1572066

[27] Coxhead, A., 2000. A new academic word list. TESOL Quarterly. 32(4), 213–238. DOI: https://doi.org/10.2307/3587951

[28] Gardner, D., Davies, M., 2014. A new academic vocabulary list. Applied Linguistics. 35(3), 305–327. DOI: https://doi.org/10.1093/applin/amt015

[29] Corson, D.J., 1985. Education for work: Reflections towards a theory of vocational education. International Review of Education. 31(1), 283–302. DOI: https://doi.org/10.1007/BF02262583

[30] Martin, A.V., 1976. Teaching academic vocabulary to foreign graduate students. TESOL Quarterly. 10(1), 91–97. DOI: https://doi.org/10.2307/3585942

[31] Vongpumivitch, V., Huang, J.-Y., Chang, Y.-C., 2009. Frequency analysis of the words in the academic word list (AWL) and non AWL content words in applied linguistics research papers. English for Specific Purposes. 28(1), 33–41. DOI: https://doi.org/10.1016/j.esp.2008.08.003

[32] Yuan, X., Tang, X., 2023. Effects of morphological intervention on multiple aspects of academic vocabulary knowledge. Acta Psychologica. 234, 103869. DOI: https://doi.org/10.1016/j.actpsy.2023.103869

[33] Arad, M., 2003. Locality constraints on the interpretation of roots: The case of Hebrew denominal verbs. Natural Language & Linguistic Theory. 21(4), 737–778. DOI: https://doi.org/10.1023/A:1025533719905

[34] Read, J., Chapelle, C.A., 2001. A framework for second language vocabulary assessment. Language Testing. 18(1), 1–32. DOI: https://doi.org/10.1177/026553220101800101

[35] Wesche, M., Paribakht, T.S., 1996. Assessing second language vocabulary knowledge: Depth versus breadth. Canadian Modern Language Review. 53(1), 13–40. DOI: https://doi.org/10.3138/cmlr.53.1.13

[36] Waring, R., 2002. Scales of vocabulary knowledge in second language vocabulary assessment. Kiyo, Occasional Papers of Notre Dame Seishin University. 26(1), 40–54.

[37] Zhong, H., 2012. Multidimensional vocabulary knowledge: Development from receptive to productive use. In: Hirsh, D. (Ed.). Current Perspectives in Second Language Vocabulary Research. Peter Lang: Lausanne, Switzerland. pp. 23–55.

[38] Schmitt, N., Zimmerman, C.B., 2002. Derivative Word Forms: What do learners know? TESOL Quarterly. 36(2), 145–171. DOI: https://doi.org/10.2307/3588328

[39] Pellicer Sánchez, A., Schmitt, N., 2012. Scoring yes–no vocabulary tests: Reaction time vs. nonword approaches. Language Testing. 29(4), 489–509. DOI: https://doi.org/10.1177/0265532212438053

[40] Rasch, G., 1960. Studies in Mathematical Psychology I: Probabilistic Models for Some Intelligence and Attainment Tests. The Danish Institute for Educational Research: Copenhagen, Denmark.

[41] Wright, B.D., Stone, M., 1999. Measurement Essentials, 2nd ed. Wide Range: Wilmington, DE, USA.

[42] Linacre, J.M., Wright, B.D., 1993. Constructing linear measures from counts of qualitative observations. In Proceedings of the Fourth International Conference on Informetrics and Scientometrics, Berlin, Germany, 11–15 September 1993.

[43] Cohen, J., 1988. Statistical Power Analysis for the Behavioral Sciences, 2nd ed. Routledge: New York, NY, USA.

[44] Goulden R, Nation P, Read, J., 1990. Read J. How large can a receptive vocabulary be? Applied linguistics. 11(4), 341–363.

[45] Franz, J., Teo, A., 2018. ‘A2 is normal’ — Thai secondary school English teachers’ encounters with the CEFR. RELC Journal. 49(3), 322–338. DOI: https://doi.org/10.1177/0033688217738816

[46] Nation, I.S.P., 2012. Measuring vocabulary size in an uncommonly taught language. In Proceedings of the International Conference on Language Proficiency Testing in the Less Commonly Taught Languages, Bangkok, Thailand, 17–18 August 2012.

[47] Gökcan, M., Aktan, D.Ç., 2022. Validation of the vocabulary size test. Journal of Measurement and Evaluation in Education and Psychology. 13(4), 305–327. DOI: https://doi.org/10.21031/epod.1144808

[48] Asquith, S., 2022. An investigation into the roles of guessing and partial knowledge in the vocabulary size test. TESL-EJ. 26(3), n3. DOI: https://doi.org/10.55593/ej.26103a15

[49] Webb, S., Sasao, Y., Ballance, O., 2017. The updated vocabulary levels test: Developing and validating two new forms of the VLT. ITL – International Journal of Applied Linguistics. 168(1), 33–69. DOI: https://doi.org/10.1075/itl.168.1.02web

[50] Masrai, A., Milton, J., 2018. Measuring the contribution of academic and general vocabulary knowledge to learners' academic achievement. Journal of English for Academic Purposes. 31, 44–57. DOI: https://doi.org/10.1016/j.jeap.2017.12.006

[51] Evans, S., Green, C., 2007. Why EAP is necessary: A survey of Hong Kong tertiary students. Journal of English for Academic Purposes. 6(1), 3–17. DOI: https://doi.org/10.1016/j.jeap.2006.11.005

[52] Warnby, M., 2023. Academic vocabulary knowledge among adolescents in university preparatory programmes. Journal of English for Academic Purposes. 61, 101203. DOI: https://doi.org/10.1016/j.jeap.2022.101203

[53] Min, C., Sukying, A., 2024. Investigating the role of word knowledge components in Chinese L2 writing ability. 3L: Southeast Asian Journal of English Language Studies. 30(4), 273–290. DOI: http://dx.doi.org/10.17576/3L-2024-3004-19

[54] Nagy, W., Townsend, D., 2012. Words as tools: Learning academic vocabulary as language acquisition. Reading Research Quarterly. 47(1), 91–108. DOI: https://doi.org/10.1002/RRQ.011

[55] Van Vu, D., Michel, M., 2021. An exploratory study on the aspects of vocabulary knowledge addressed in EAP textbooks. Dutch Journal of Applied Linguistics. 10. DOI: https://doi.org/10.51751/dujal9345

[56] Nacira, G., 2010. Identification and analysis of some factors behind students’ poor writing productions: The case study of 3rd year students at the English department-Batna University [Master’s thesis]. University of Setif: Setif, Algeria.

[57] Snow, C.E., Uccelli, P., 2009. The challenge of academic language. In: Olson, D.R., Torrance, N. (Eds.). The Cambridge Handbook of Literacy. Cambridge University Press: Cambridge, UK. pp. 112–133.

[58] Teng, M.F., 2024. The roles of second-language proficiency level and working memory on vocabulary learning from word-focused exercises. RELC Journal. 55(2), 296–312. DOI: https://doi.org/10.1177/00336882221102228

[59] Hyland, K., Tse, P., 2007. Is there an “academic vocabulary”? TESOL Quarterly. 41(2), 235–253. DOI: https://doi.org/10.1002/j.1545-7249.2007.tb00058.x

[60] Baumann, J.F., Graves, M.F., 2010. What is academic vocabulary? Journal of Adolescent & Adult Literacy, 54(1), 4–12. DOI: https://doi.org/10.1598/JAAL.54.1.1

[61] González-Fernández, B., Schmitt, N., 2020. Word knowledge: Exploring the relationships and order of acquisition of vocabulary knowledge components. Applied Linguistics. 41(4), 481–505. DOI: https://doi.org/10.1093/applin/amy057

[62] Schmitt, N., 1998. Tracking the incremental acquisition of second language vocabulary: A longitudinal study. Language Learning. 48(2), 281–317. DOI: https://doi.org/10.1111/1467-9922.00042

[63] Masrai, A., Milton, J., El-Dakhs, D.A.S., et al., 2021. Measuring the contribution of specialist vocabulary knowledge to academic achievement: Disentangling effects of multiple types of word knowledge. Asian-Pacific Journal of Second and Foreign Language Education. 6(1), 8. DOI: https://doi.org/10.1186/s40862-021-00114-5

Downloads

How to Cite

Namsaeng, P., Sukying, A., & Phusawisot, P. (2025). Examining the Link between Thai L2 University Students’ Vocabulary Size and Academic Vocabulary Depth. Forum for Linguistic Studies, 7(12), 351–363. https://doi.org/10.30564/fls.v7i12.11926

Issue

Vol. 7 , Iss. 12 (December 2025): In progress

Article Type

Article

License

Copyright © 2025 Pasara Namsaeng, Apisak Sukying, Pilanut Phusawisot

Creative Commons License

This is an open access article under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License.