The reliability of language-switch costs in bilingual one- and two-digit number naming

Abstract

Aims and objectives/purpose/research questions: Language-switch costs, which denote worse performance in language-switch than in language-repetition trials, appear to be a robust finding in bilingual language switching. The aim of the present study was to examine the intraindividual reliability of language-switch costs by means of a number-naming task with German-English bilinguals. Design/methodology/approach: In a cued language-switching paradigm, participants ( n = 36) switched between German and English. They performed a number-naming task in three different conditions: one-digit numbers; two-digit numbers with decade 10; and two-digit numbers with decade 20. Data and analysis: We examined the experimental effects with an analysis of variance (reaction time and error rate as the dependent variables), using trial language, language sequence and number condition as independent variables. In addition, we calculated the split-half reliability of language-switch costs (across all conditions) as well as the correlations of language-switch costs between the different conditions. Findings/conclusions: While significant language-switch costs emerged in all three number conditions, our results demonstrate a medium-sized correlation between the three experimental conditions. The split-half reliability shows a moderate to strong correlation between the odd- and even-numbered trials in the experiment. Originality: On the one hand, the present study extends the observation of language-switch costs from one-digit number naming to the more complex naming of two-digit numbers. On the other hand, and theoretically even more important, we explored the reliability of language-switch costs in a bilingual number-naming task by calculating both split-half reliability and correlations between different number conditions. Significance/implications: The results indicated that while language-switch costs are a robust experimental effect on the group level, they appear to be less well suited for correlational approaches. This also suggests that caution should be exerted when language-switch costs are used to diagnose the ability of an individual to perform language control.