- This chapter presents the research methodology used in the study

- Research design and data collection process are described in detail

- The chapter explains the quantitative and qualitative data analysis methods used in the study

- This chapter provides an overview of the background literature on receptive vocabulary breadth and cross-linguistic influence

- The chapter also discusses previous research on receptive vocabulary breadth in Chinese as a foreign/second language learners from different language backgrounds

- The theoretical framework and concept of receptive vocabulary breadth are introduced in this chapter

1. Introduction

This chapter introduces the importance of heritage language (HL) learning and the need to understand the differences in vocabulary knowledge between HL and non-HL learners. It also discusses the concept of vocabulary breadth and the lack of research comparing vocabulary breadth among HL and non-HL learners. Additionally, the chapter presents the increasing interest in Chinese as a heritage language (CHL) research and the need for cross-country comparative studies to understand the impact of CHL background on Chinese vocabulary breadth.

2. Literature Review

This chapter discusses the importance of vocabulary in language acquisition, the ecological approach to second language acquisition, influencing factors on vocabulary acquisition, and the benefits of mixed-methods research on vocabulary acquisition among heritage language (HL) learners. It also highlights the gaps in the literature and introduces the research questions for the current study.

3. Method

This chapter describes the methodology used in the study, including the recruitment of participants from Indonesia and Thailand, the use of a broad definition for heritage language (HL) learners, and the instruments used to measure receptive vocabulary breadth. The study employed a mixed-methods approach, collecting quantitative data through a Chinese vocabulary proficiency test and qualitative data through semi-structured interviews. The participants' Chinese language proficiency was self-reported due to the COVID-19 pandemic, and the online administration of the quantitative data and interviews was carried out using Zoom or Google Classroom. The Chinese vocabulary proficiency test included 100 words and was validated based on the Rasch model, while the semi-structured interviews were transcribed and analyzed using a thematic analytical approach.

4. Results

The findings indicated that CHL background significantly predicted CVPT scores only in the Indonesian group, not in the Thai group. The results showed that CHL background did not predict the participants’ CVPT scores, but the interaction between CHL and country background significantly predicted the participants’ CVPT scores at the beginner-level vocabulary. Interview data analysis pointed to individual differences, family background and neighborhood contexts, Chinese language education, and socio-cultural factors as potential contributors to the varying impacts of CHL background on Chinese vocabulary breadth. In terms of motivation, the interview data did not reveal any obvious differences in motivations toward Chinese learning between CHL learners and non-CHL learners in Indonesia and Thailand. As for the vocabulary learning strategies, all the learners interviewed mentioned some common strategies, such as repeated writing or keeping an electronic or pencil-and-paper vocabulary notebook, associating the meanings of the words and Hanzi. The first difference was related to the linguistic environment at home and neighborhood. According to all the Indonesian interviewees, Chinese Indonesians in most areas of Indonesia frequently communicated with family members and neighbors using Chinese dialects, and Chinese Indonesian parents encouraged their children to inherit Chinese language and cultures. In contrast, the Thai participants reported that most Chinese Thais used Thai instead of Mandarin or Chinese dialects to communicate with family members and neighbors.

5. Discussion

This chapter discussed the differences in the predictive power of CHL background on Chinese receptive vocabulary breadth between Indonesian and Thai groups, with a stronger impact observed in the Indonesian group. The study found that CHL background could facilitate the acquisition of receptive vocabulary breadth among Indonesian CHL learners, but not in the Thai group. The influencing factors on the different effects of CHL background on vocabulary breadth were explained from the perspective of ecological system theory, including macrosystem, exosystem, mesosystem, and microsystem. The interaction effect between country and CHL background was only observed at the beginner-level vocabulary, and the study has significant implications for theories concerning HL acquisition and practical implications for Chinese language instruction for CHL learners.

6. Conclusion and Limitations

The present study has some limitations, including the participants being beginning and intermediate CS/FL learners from Indonesia and Thailand, and the challenge of accounting for potential moderating variables. The study also noted the need for more evidence regarding the representation of participants in the quantitative section. Furthermore, the participants’ Chinese proficiency was mainly assessed by self-report due to the COVID-19 pandemic, and future research is advised to measure Chinese proficiency from multiple dimensions. Despite these shortcomings, the study may be the first to explore the interaction effect of CHL and country background on vocabulary breadth and could provide insight into how CHL background influences language acquisition in different contexts.