Item repetition matters: methodological considerations in bilingual language control research

Language switching experiments often vary in stimuli list sizes, leading to differences in item repetition frequency and potentially obscuring our understanding of bilingual language control. This study addresses how item repetition frequency affects switching costs and the reversed language dominance effect (i.e. better performance in a non-dominant language in mixed language naming) among bilinguals with varying L2 proficiencies, and how these effects evolve as the task progresses. Two experiments were conducted with 29 low- and 36 high-proficiency Chinese-English bilinguals using a picture naming task. One experiment presented a low-repetition stimuli list, and the other a high-repetition set. Results showed that switching costs remained regardless of item repetition frequency. However, the influence of L2 proficiency and language dominance on switching costs was only evident in the low-repetition list. Notably, as the task progressed, switching costs decreased in L1 Chinese but increased in L2 English, regardless of item repetition frequency or proficiency. These findings highlight the importance of methodological considerations in language control experiments. Understanding how these factors influence the experiments’ outcomes is crucial for accurately interpreting bilingual language control and avoiding undesirable confounds.