We compared 121 native and 114 non-native speakers of Dutch (with 35 different first languages) on four digit-span tasks, varying modality (visual/auditory) and direction (forward/ backward). An interaction was observed between nativeness and modality, such that, while natives performed better than the non-natives on the auditory tasks (which were performed in the non-natives' second language), performance on the visual tasks (which was performed in participants' dominant language) did not significantly differ between natives and non-natives. The interaction between nativeness and modality disappeared when the data were corrected for Dutch proficiency. Correction for Dutch proficiency elevated non-native speakers' scores on the auditory tasks, without altering the non-natives' digit-span rank order. Despite considerable differences in mean length of the digit names zero to nine in the non-natives' first languages, these differences were not significantly correlated with their visual digit-span scores. While further research is needed on the sources of variation in digit-span performance, we recommend the use of the visual digit-span task (forward or backward) for cross-linguistic research and advise researchers to be aware of the association between language proficiency and verbal workingmemory performance.
KeywordsBilingual digit span, visual digit span, auditory digit span, forward digit span, backward digit span, verbal working memory