Modeling individual differences in vocabulary development: A large‐scale study on Japanese heritage speakers
2025

Vocabulary Development in Japanese Heritage Speakers

Sample size: 563 publication 10 minutes Evidence: high

Author Information

Author(s): Maki Kubota, Jason Rothman

Primary Institution: University of Bergen

Hypothesis

When does the vocabulary knowledge of Japanese heritage speakers begin to diverge from their monolingual counterparts?

Conclusion

Japanese heritage speakers begin to show lower vocabulary scores than their monolingual peers starting at around 5.61 years of age, with this difference persisting into young adulthood.

Supporting Evidence

  • Vocabulary scores for monolinguals averaged 46.36, while heritage speakers averaged 45.28.
  • Significant differences in vocabulary scores between heritage speakers and monolinguals began at age 5.61.
  • Six latent factors were identified that influence vocabulary development: Holiday, School, Community, Proficiency, Literacy, and Home.

Takeaway

Kids who speak Japanese at home and in their community start to know fewer words than kids who only speak Japanese at around 5 years old, and this difference continues as they grow up.

Methodology

The study used structural equation modeling to analyze vocabulary scores and factors influencing vocabulary development in a large sample of Japanese heritage speakers and monolinguals.

Potential Biases

Potential biases may arise from self-reported measures of proficiency and vocabulary.

Limitations

The study is cross-sectional and does not track individual development over time.

Participant Demographics

Participants included 427 Japanese heritage speakers (mean age 9.96, 213 female) and 136 monolingual Japanese children (mean age 6.69, 65 female).

Statistical Information

P-Value

<0.001

Confidence Interval

95% CI

Statistical Significance

p<0.001

Digital Object Identifier (DOI)

10.1111/cdev.14168

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