This study investigates the relationship between language and cognition by examining attention to grammatical number among Thai and English speakers within the framework of linguistic relativity. Three comparisons were conducted: 60 native Thai and 60 native English speakers; 30 Thai monolingual speakers and 30 Thai-English bilingual speakers; and 30 Thai-English bilingual speakers at different levels of English proficiency, classified as low, medium, and high, with 10 participants at each level. Participants were at least 20 years old and selected through purposive sampling. Attention to grammatical number was elicited through picture-description tasks. Bilingual participants’ English proficiency was assessed using researcher-developed listening and speaking tasks based on sentence-complexity criteria. The data were analysed using descriptive statistics, independent-samples t-tests for the two-group comparisons, the Kruskal-Wallis H test for the three proficiency groups, and regression analysis to examine the relationship between English proficiency and attention to grammatical number. The results revealed that (1) native English speakers exhibited significantly greater attention to grammatical number than native Thai speakers; (2) Thai-English bilingual speakers demonstrated greater attention than Thai monolingual speakers, although the difference was not statistically significant; and (3) among bilingual participants, attention to grammatical number differed significantly across proficiency levels, with higher-proficiency participants demonstrating greater attention than lower-proficiency participants. Regression analysis further indicated a strong positive relationship between English proficiency and attention to grammatical number. These findings provide empirical support for the Linguistic Relativity Hypothesis, suggesting that the relationship between language and cognition extends beyond native language structure to subsequent linguistic experience and second-language proficiency.

Keywords: Linguistic Relativity Hypothesis; Grammatical Number; Bilingualism; Attention; Second Language Acquisition

Aemdit, C. (2015). The relationship between grammatical tense marking and the cognitive system: A test of the linguistic relativity hypothesis in English, Japanese, Chinese, and Thai [Doctoral dissertation, Chulalongkorn University].

Aemdit, C., & Prasithrathsint, A. (2016). The influence of English language on bilinguals' cognition: A test of the linguistic relativity hypothesis in Thai speakers. Sripatum Review of Humanities and Social Sciences, 16(2), 7-16.

Alebaid, M. (2021). The effects of first language on the learning of English as a second language. Multi-Knowledge Electronic Comprehensive Journal for Education and Science Publications (MECS), 44, 1-16.

Athanasopoulos, P. (2006). Effects of the grammatical representation of number on cognition in bilinguals. Bilingualism: Language and Cognition, 9(1), 89-96.

Athanasopoulos, P. (2007). Interaction between grammatical categories and cognition in bilinguals: The role of proficiency, cultural immersion, and language of instruction. Language and Cognitive Processes, 22(5), 689-699.

Athanasopoulos, P. (2009). Cognitive representation of color in bilinguals: The case of Greek blues. Bilingualism: Language and Cognition, 12, 83-95.

Athanasopoulos, P. (2011). Color and bilingual cognition. In V. Cook & B. Bassetti (Eds.), Language and bilingual cognition (pp. 241-262). Psychology Press.

Atthaphonphiphat, S. C. (2015). Error analysis in English essay writing of Suratthani Rajabhat University’s students with different English language experiences. Journal of Humanities and Social Sciences Suratthani Rajabhat University, 7(1), 25-52.

Barner, D., Inagaki, S., & Li, P. (2009). Language, thought, and real nouns. Cognition, 111, 329-344.

Boroditsky, L. (2001). Does language shape thought? Mandarin and English speakers’ conceptions of time. Cognitive Psychology, 43(1), 1-22.

Chandharath, W. (2013). The relationship between linguistic honorifics and the cognitive systems of Japanese, Thai, and English [Master’s thesis, Chulalongkorn University].

Chanyeam, C., & Wongthai, N. (2025). The influence of grammatical number on cognition of bilinguals: A test of the linguistic relativity hypothesis. LEARN Journal: Language Education and Acquisition Research Network, 18(1), 405-432.

Charunrochana, J. (2000). The relationship between nominal grammatical categories and the cognitive system of Thai and English speakers [Doctoral dissertation, Chulalongkorn University].

Chen, Z., & Faitaki, F. (2025). Effects of the French grammatical gender system on bilingual adults’ perception of objects. Bilingualism: Language and Cognition, 28(2), 401-414.

Chi Pech, J. I. (2024). Using cognitive measures from linguistic relativity research to assess thinking in Yucatec Maya-Spanish bilingual children. First Language, 44(6), 708-733.

Covington, M. A., He, C., Brown, C., Naçi, L., & Brown, J. (2006). How complex is that sentence? A proposed revision of the Rosenberg and Abbeduto D-level scale (CASPR Research Report 2006-01). University of Georgia, Artificial Intelligence Center.

Friedenberg, J., & Silverman, G. (2006). Cognitive science: An introduction to the study of mind. SAGE.

Gordon, P. (2004). Numerical cognition without words: Evidence from Amazonia. Science, 306, 496-499.

Groome, D. (2014). An introduction to cognitive psychology: Processes and disorders. Psychology Press.

Humboldt, W. (1988). On language: The diversity of human language-structure and its influence on the mental development of mankind. Cambridge University Press.

Jawaut, N., Pokaisawan, C., & Puangchalam, Y. (2023). A study of common grammatical errors in Thai to English translation of students from English program in a Thai Rajabhat University. In Proceedings of the 15th NPRU National Academic Conference 2023 (pp. 2043-2054).

Li, P., Dunham, Y., & Carey, S. (2009). Of substance: The nature of language effects on entity construal. Cognitive Psychology, 58, 487-524.

Lucy, J. (1992). Grammatical categories and cognition: A case study of the linguistic relativity hypothesis. Cambridge University Press.

Majid, A., Roberts, S. G., Cilissen, L., Emmorey, K., Nicodemus, B., O’Grady, L., Woll, B., Lelan, B., De Sousa, H., Cansler, B. L., & Levinson, S. C. (2020). Differential coding of perception in the world’s languages. Proceedings of the National Academy of Sciences, 117(38), 23361-23368.

Ninpanit, S., & Pongpairoj, N. (2016). The acquisition of the English plural morpheme by L1 Thai learners: A case of the failed functional features hypothesis. Pasaa Paritat Journal, 31, 53-80.

Pappol, R., Nakcharoen, J., & Sukpatcharaporm, N. (2022). Error analysis of written English essays: The case of 3rd year students of English major, Chiang Mai Rajabhat University. Phimoldhamma Research Institute Journal, 9(1), 1-13.

Pawabutra, P., & Sutakote, C. (2024). An analysis of grammatical errors in English speaking of Thai EFL learners. Journal of English Language and Linguistics, 5(3), 297-313.

Prasithrathsint, A. (2006). The making of a linguist. Chulalongkorn University Press.

Romero, Y., & Manjarres, M. P. (2017). How does the first language have an influence on language learning? A case study in an English ESL classroom. English Language Teaching, 10(7), 123-139.

Saalbach, H., & Imai, M. (2007). Scope of linguistic influence: Does a classifier system alter object concept? Journal of Experimental Psychology: General, 136, 485-501.

Siriwittayakorn, T., & Miyamoto, E. T. (2019). Thai learners of English are sensitive to number-agreement violations. In Proceedings of the 33rd Pacific Asia Conference on Language, Information and Computation (PACLIC 33) (pp. 237-243).

Sridhanyarat, K. (2017). The acquisition of L2 fricatives in Thai learners’ interlanguage. 3L: The Southeast Asian Journal of English Language Studies, 23(1), 15-34.

Thongniam, K. (2017). The effect of grammatical gender on cognition of Russian-English bilinguals compared with Russian monolinguals and English monolinguals [Master’s thesis, Chulalongkorn University].

Thongniam, K., & Prasithrathsint, A. (2020). The influence of grammatical gender on Russian and Thai speakers’ cognition. Manusya: Journal of Humanities, 23(1), 40-59.

Timyam, N. (2018). Patterns and causes of deviations in English verbal inflectional suffixes among Thai ELF learners. 3L: The Southeast Asian Journal of English Language Studies, 24(1), 1-15.

Watcharapunyawong, S., & Usaha, S. (2013). Thai EFL students’ writing errors in different text types: The interference of the first language. English Language Teaching, 6(1), 67-78.