An interlanguage study of lexical priming and the acquisition of English vocabulary by L1 Thai learners
Authors:   , It-ngam Suparuthai 
Published: September 2023

The present study explored English vocabulary acquisition of L1 Thai learners. The lexical priming, which implies the lexical access, was examined to illustrate the vocabulary acquisition. The organization of the mental lexicon and the lexical processing of Thai learners were examined using the lexical priming experiments. The factors affecting the vocabulary acquisition were also investigated through qualitative approach. The present interlanguage study is a cross-sectional research that compared the English vocabulary acquisition of the learners with different degrees of language exposure. The sample groups were selected by stratified random sampling. They were Thai undergraduates who were living in Thailand. The English Language Exposure (ELE) Questionnaires were distributed to 620 students, then 90 students were selected by their English language exposure scores. High Exposure (HE) group and Low Exposure (LE) group were the top 45 students with the highest exposure scores, and the bottom 45 students with the lowest scores accordingly. Two psycholinguistic tasks, i.e., Lexical Decision Task-LDT (Rubenstien, Garfield & Millikan, 1970) and Word Association Task-WAT (McNeil, 1966) were conducted to explore the organization of the mental lexicon and the lexical processing of these two groups of participants. The participants also took the Vocabulary Size Test (Nation & Beglar, 2007) to measure their vocabulary knowledge. Twenty-two participants who had different degrees of language exposure and vocabulary size were selected as the focus group to take part in the qualitative investigation of the factors affecting vocabulary acquisition. There were 4 sub-groups: the HE-group with large vocabulary size (HE-LV), the HE-group with small vocabulary size (HE-SV), the LE-group with large vocabulary size (LE-LV), and the LE-group with small vocabulary size (LE-SV). They were to complete the vocabulary learning journal and were interviewed. The responses related to language learning resources were reported and their quality of the exposures was evaluated. The findings from the LDT showed that the average reaction time of the collocation was faster than the non-collocation and nonword. The findings from the WAT exhibited that words were stored closely based on meanings-or grammatically related positions. The findings showed that words were mainly associated to each other by meanings and concepts. The results partly support (Hoey, 2005) that, in a part of the mental lexicon, the frequently co-existing words (e.g., feel-pain) are stored closely together. The comparison between the HE-group and LE-group confirmed the hypothesis that the 2 groups of learners had different structures of the mental lexicon organization, and different paths in lexical access of the L2 words. The HE-group seemed to have the stronger links between words in the L2 mental lexicon than the LE-group with faster response rates and fewer errors in LDT. The HE-group was able to produce a greater number of meaningful chunks in WAT than the LE-group. The LE-group exhibited some L1 transfer which is commonly found in L2 learners who were from the non-English speaking countries. The results from the qualitative study of factors related to vocabulary acquisition showed 4 main factors related to their acquisition, i.e., degrees of language exposure, vocabulary size, vocabulary learning methods, and attitudes towards English language. The lexical processing of the HE-group was more proficient than the LE-group. The results also showed that, with the sufficient numbers of words (at least 3,000 words), the organization of the mental lexicon of the HE-LV, HE-SV, and LE-LV were meaning-based, which is similar to native speakers. The learners who had quite a large vocabulary size were able to manage their autonomous learning from language learning resources. With good attitudes towards English language (affection, high-motivation and self-esteem), the HE-LV learners seem to be the most successful group in vocabulary acquisition.