Hi there!

I am currently a postdoctoral researcher working with Dr. Reiko Mazuka at RIKEN CBS Laboratory for Language Development (previously at Dr. Krista Byers-Heinlein's Concordia Infant Research Laboratory). My main research interests are centered around infant language development, bilingualism, and cross-cultural/cross-language differences. I am particularly interested in studying how differences in language environment influence early language development.

One thing I enjoy doing in research is analyzing and visualizing data. Often time I’m amazed by what the data tells us about language development in infants.

On a side note, I am also multilingual. Growing up in Hong Kong, I speak Cantonese, English, and Mandarin Chinese; I also learned Japanese since teenage years.

Please feel free to contact me if you have any questions relating to my research.

Rachel :)

You can take a look at my CV here.

  • Infant speech perception
  • Early language development
  • Bilingualism
  • Cross-cultural differences
  • Language dominance / Parental language input
  • Lexical tones and intonation
  • Data visualization
  • PhD in Speech and Hearing Sciences, 2019

    The University of Hong Kong

  • MA in Linguistics, 2014

    The University of Hong Kong

  • BA in Japanese Language and Literature & Linguistics (double-major), 2013

    University of California, Berkeley

Research Experience

Postdoctoral researcher
Feb 2021 – Present Wako, Saitama, Japan

Cross-cultural research on infant language and social skill development supervised by Dr. Reiko Mazuka

  • A large-scale international collaboration project including 6 countries
  • Online international seminar series working with overseas speakers
Postdoctoral fellow
Sep 2019 – Jan 2021 Montreal, QC, Canada

Bilingual infant language development research supervised by Dr. Krista Byers-Heinlein

  • A computational model study looking at how bilingual infants learn translation equivalent (e.g., “apple” in English and “pomme” in French refers to the same fruit)
  • A longitudinal online study which tracks vocabulary development in bilingual infants
  • An online tablet study which I coded and programmed to test bilingual children’s vocabulary learning
  • A longitudinal international collaboration project with Princeton University
  • Co-supervising an honor undergraduate student with Dr. Byers-Heinlein
Doctoral researcher
Division of Speech and Hearing Sciences, The University of Hong Kong
Sep 2015 – Aug 2019 Hong Kong
  • Infant language development study looking at how Cantonese-learning infants under the age of 12 months acquire their native lexical tonese
  • Cantonese intonation study with Cantonese-speaking adults
  • Phonetic study with Cantonese-English bilingual adults / English-learning school-aged children

Recent Talks

Presentations made at international conferences

A multi-lab study of gaze-following development in monolingual and bilingual infants
Using a multi-lab collaborative approach, we investigated whether language experience could affect the development of gaze-following. Independent of monolingual or bilingual status, early gaze-following development is significantly modulated by age-related changes.


Quickly discover relevant content by filtering publications.
(2021). How open science can benefit bilingualism research: A lesson in six tales. PsyArXiv.


(2020). The development of gaze following in monolingual and bilingual infants: A multi-laboratory study. infancy, 26(1), 4-38.

PDF Cite Code Dataset DOI

(2019). Impact of language dominance on phonetic transfer in Cantonese–English bilingual language switching. Applied Psycholinguistics, 40(1), 29-58.



  • rachelkytsui [at] gmail.com
  • Laboratory for Language Development,
    RIKEN Center for Brain Science,
    Information Science Building,
    2-1 Hirosawa, Wako-shi,
    Saitama, Japan 351-0198