Research themes

My research projects lie in three areas under childhood multilingualism and adult second language (L2) acquisition:

  1. Childhood multilingualism: Simultaneous and sequential development of two or more languages involving Chinese and English in infants and preschool children
  2. Heritage Chinese: Development, ultimate attainment and attrition of the grammatical system in heritage language speakers of Chinese across the life span
  3. Adult L2 Chinese: Functional categories in adult second language (L2) speakers of Chinese, aspect markers, focus-sensitive particles and grammatical constructions subject to multi-level interface conditions (e.g. ba, bei, topic and cleft)

I explore these topics through a combination of corpus, experimental and statistical methods.

Research grants in PI capacity


  • Input and experience in early trilingual development (General Research Fund/GRF, Research Grants Council of Hong Kong/RGC, Project No. 14615820, 2021-2023, $977,820), RGC intro page
  • Input and caretaker proficiency in early bilingual development: mothers, helpers and toddlers (Early Career Scheme/ECS, Research Grants Council of Hong Kong/RGC, Project No. 21604522, 2023-2024, $530,000), RGC intro page


  • Non-native maternal input and early bilingual development (Start-up Grant, City University of Hong Kong, 2021-2023)
  • Quantity and quality of input in early bilingual development (Direct Grant, Chinese University of Hong Kong, 2019-2020)
  • Trilingualism in early childhood: production and comprehension (Direct Grant, Chinese University of Hong Kong, 2016-2017)

Research students and assistants

Current lab members

PhD students: Miss LIANG Yuqing (2021-), Miss LIU Jingyao (2021-), Miss ZHANG Xuening (2022-)

Full-time research assistants (RA): Miss ChENG Tsz Yan Ranee, Miss CHAN Yim Han Ashley, Miss NIE Jiaqi Nicole

Former lab members

Miss CAI Qiuyun Candice (Research Assistant)

Research highlights

  • Acquisition of Chinese in English contexts: the Child Heritage Chinese Corpus (CHCC)

This project documents the language development of American-born Chinese children, who were exposed to their heritage language Chinese (Mandarin and/or Cantonese) at home, and the societal majority language English at school and at home. The corpus currently contains data from three children: Luna, Avia and Winston (LAW). An innovative feature of this corpus is the use of web-based methods (Skype) to collect the American children’s speech data. Transcripts and corresponding audio files have been deposited in CHILDES. Data from more heritage Chinese children and English-Mandarin bilingual children in Hong Kong (control group) are being collected and added to the Corpus.

  • Caretaker input and early trilingual development: the Leo Corpus, Mai & Yip (2022)

The Leo Corpus documents the simultaneous development of Mandarin, Cantonese and English in a Hong Kong child from 1;06-2;11. The family introduced an innovative “one day-one language” model on top of the “one parent-one language” system, in which the father and the grandmother spoke Mandarin to the child consistently, whereas the mother began to interact with the child in English every other day in a week and Cantonese the rest of the days. Leo successfully acquired the three languages to age-appropriate levels by 2;11. We are exploring the possibility to apply Leo’s acquisition model to other families in Hong Kong and Guangdong through a government-funded longitudinal project.

  • Realizing children’s potential in language development: input and intervention

This is a knowledge transfer project we conducted from 2018 to 2020. The project aimed to provide opportunities and materials for Cantonese-speaking preschoolers who do not have easy access to rich naturalistic input in English for them to develop English proficiency. To introduce high-quality interactive input in English, we designed and created an online intervention programme, “Learning English through Stories”, for these children (n = 160). In this programme, the children watched short story videos in English online and participated in follow-up group discussions under the guidance of their parents over 10 weeks. We tested the children with an array of language and cognitive tests before and after the intervention. A group of matched preschoolers served as the control group. The results show that children who participated in the intervention program (namely, the experimental group) displayed greater improvement in the post-test compared to those who did not participate in the course (namely, control group).