Content area
Full Text
Abstract
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 working- memory performance.
Keywords
Bilingual digit span, visual digit span, auditory digit span, forward digit span, backward digit span, verbal working memory
Introduction
Linguistic research into individual differences in language proficiency faces the challenge of finding the factors responsible for inter-individual variations. One of the factors often mentioned as a covariate is working-memory ( WM) capacity, more specifically verbal WM capacity. However, many measures of verbal WM tend to be affected by long-term memory factors such as vocabulary knowledge and familiarity with the speech sounds of a language. This is particu- larly an issue when participant samples are heterogeneous. This paper addresses the question of whether the visual digit span could be a simple verbal WM measure that can be used reliably with native and non-native speakers alike, testing verbal WM but not at the same time linguistic proficiency.
First introduced in 1974 by Baddeley and Hitch, verbal WM is just one of three modality-based components subserving the Central Executive (for an overview, see Baddeley, 2003). Also called the phonological loop, the verbal WM component allows us to store and retrieve a limited amount of phonological information, for a brief period of time. This...