Assessing of English Morpheme Acquisition Order of Thai Deaf University Students Natdanai Subin Faculty of Liberal Arts, Mahidol University, Nakhon Pathom, Thailand Krisna Lertsukprasert Department of Communication Sciences and Disorder, Mahidol University, Bangkok, Thailand Natthapong Chanyoo Faculty of Liberal Arts, Mahidol University, Nakhon Pathom, Thailand Abstract—The purposes of this study were to assess the acquisition order of nine English grammatical morphemes and to identify types of grammatical morphemes which seem difficult for Thai deaf university students. Thirty-seven Thai deaf university students completed 18 fill-in-the-blank questions. Data were analyzed by frequency, percentage, mean, and standard deviation. The results indicated that the English grammatical morpheme acquisition order of Thai deaf university students was as follows: 1) article (Mean (M) =1.38/3.00), 2) plural (M =1.36/3.00), 3) regular past tense (M =1.28/3.00), 4) progressive (M = 1.22/3.00), 5) the 3 rd person singular simple present tense (M=1.16/3.00), 6) auxiliary (M = 1.53/3.00), 7) irregular past tense (M = 1.46/3.00), 8) copula (M = 0.41/3.00), and 9) possessive (M = 0.39/3.00). From the results, the 3 rd person singular simple present tense, auxiliary, irregular past tense, copula, and possessive were considered difficult for the deaf participants. The findings from this study can be used for further pedagogical and curriculum development in teaching English grammatical morphemes to Thai deaf students. Index Terms—English morpheme acquisition, grammatical morphemes, Thai deaf university students I. INTRODUCTION Mastering the English language takes time and effort. According to Bloom and Lahey (1978), three aspects of English serve as the foundations for language development are phonemes (the sounds which represent linguistic content); morphemes (the units which indicate the meanings and forms of words); and syntax (the structures and order of words of sentences). Figure 1 shows the levels in language development proposed by Bloom & Lahey in 1978. Hearing students usually develop an awareness of these three linguistic features prior to developing semantical knowledge (the meanings of phrases and sentences) and pragmatical knowledge (the actual use of language in specific contexts). In contrast, students with a hearing disability, especially with profound deafness, may lack phonological input and thus phonological knowledge. As a result, students who are profoundly deaf have to heavily rely upon morphemes and syntax. Deaf students typically develop gesture-based communication based primarily on a finite set of signed words with iconicity (Liddell, 1984; Wilbur, 1987). Iconicity refers to the degree of a resemblance between a gestural sign and a word. Since the language learning pathways and communication systems of the deaf are different from their hearing counterparts, the morphological development and knowledge of these two groups of students are also different. Figure 1. Proposed Levels in Language Development II. LITERATURE REVIEW Language Use (Pragmatics) Language Content (Semantics) Language Forms (Phonology, Morphology, Syntax) ISSN 1798-4769 Journal of Language Teaching and Research, Vol. 13, No. 3, pp. 525-532, May 2022 DOI: https://doi.org/10.17507/jltr.1303.08 © 2022 ACADEMY PUBLICATION