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Using lexical diversity measures to operationalise language dominance in bilinguals

Treffers-Daller, J. and Korybski, T. (2015) Using lexical diversity measures to operationalise language dominance in bilinguals. In: Silva-Corvalan, C. and Treffers-Daller, J. (eds.) Language dominance in bilinguals: issues of measurement and operationalization. Cambridge University Press, Cambridge, pp. 106-123. ISBN 9781107044494

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Treffers-Daller and Korybski propose to operationalize language dominance on the basis of measures of lexical diversity, as computed, in this particular study, on transcripts of stories told by Polish-English bilinguals in each of their languages They compute four different Indices of Language Dominance (ILD) on the basis of two different measures of lexical diversity, the Index of Guiraud (Guiraud, 1954) and HD-D (McCarthy & Jarvis, 2007). They compare simple indices, which are based on subtracting scores from one language from scores for another language, to more complex indices based on the formula Birdsong borrowed from the field of handedness, namely the ratio of (Difference in Scores) / (Sum of Scores). Positive scores on each of these Indices of Language Dominance mean that informants are more English-dominant and negative scores that they are more Polish-dominant. The authors address the difficulty of comparing scores across languages by carefully lemmatizing the data. Following Flege, Mackay and Piske (2002) they also look into the validity of these indices by investigating to what extent they can predict scores on other, independently measured variables. They use correlations and regression analysis for this, which has the advantage that the dominance indices are used as continuous variables and arbitrary cut-off points between balanced and dominant bilinguals need not be chosen. However, they also show how the computation of z-scores can help facilitate a discussion about the appropriateness of different cut-off points across different data sets and measurement scales in those cases where researchers consider it necessary to make categorial distinctions between balanced and dominant bilinguals. Treffers-Daller and Korybski correlate the ILD scores with four other variables, namely Length of Residence in the UK, attitudes towards English and life in the UK, frequency of usage of English at home and frequency of code-switching. They found that the indices correlated significantly with most of these variables, but there were clear differences between the Guiraud-based indices and the HDD-based indices. In a regression analysis three of the measures were also found to be a significant predictor of English language usage at home. They conclude that the correlations and the regression analyses lend strong support to the validity of their approach to language dominance.

Item Type:Book or Report Section
Divisions:Arts, Humanities and Social Science > Institute of Education > Language and Literacy in Education
Interdisciplinary Research Centres (IDRCs) > Centre for Literacy and Multilingualism (CeLM)
ID Code:39019
Uncontrolled Keywords:bilingualism, language dominance, cross-linguistic influence, bilingual first language acquisition, fluency, language proficiency, language processing in bilinguals, domains of language use, input in bilingual first language acquisition
Publisher:Cambridge University Press
Publisher Statement:This chapter has been accepted for publication and will appear in a revised form, subsequent to appropriate editorial input by Cambridge University Press, in Language dominance in bilinguals: issues of measurement and operationalization published by Cambridge University Press.


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