Language control in bilinguals is often investigated with the language switching paradigm. Switch costs reflect the ease/difficulty of applying this control mechanism. The type of stimuli employed in the experiments may influence switch costs. To date, only one study has compared digit vs picture processing, reporting reduced switch costs for digits (Declerck, Koch & Philipp, 2012). This result was adjudicated to phonological overlap between the languages used. Crucially, it remains an open question whether this digit effect generalises to language combinations without phonological relation. We fill this gap by investigating language switching with two language pairs differing in relative proficiency (L1 Chinese–L2 English, L1 Chinese–L3 French), where cross-language phonological activation is not expected. Overall, a digit effect is observed in the Chinese–English pair. Contrary to Declerck et al.'s (2012) finding, digits increased switch costs. Phonological mediation cannot explain this effect; instead, we suggest its origin lies in within-language word association links.

Previous studies have demonstrated that language switching in bilinguals can be affected by a number of variables, including the processing context. Here, we used a modified language-switching task combined with a Stroop paradigm, which manipulated the context of the task, to examine the impact of processing context on switch costs. The results of both Experiment 1 and Experiment 2 showed that the switch costs and the level of asymmetry in the switch costs are larger in the conflicting context than in the non-conflicting context, suggesting that the processing context affects the switch costs. In addition, the results of Experiment 2 revealed that individual variances in cognitive control capacity also play a role in the overall magnitude of the switch costs. Critically, processing context effects can be modulated by individual variance in cognitive control capacities. The results of this study are discussed within the framework of classic models of bilingual language control (e.g., the inhibitory control model).

Bilinguals dynamically activate lexical items in one or both languages depending on a number of factors. We explored the interaction effects of semantic constraints, language context, and L2-proficiency on cross-language interaction and switch costs in bilinguals who habitually codeswitch between Algerian Arabic (AA) and French. We recorded response times to French cognates and non-cognates embedded in auditory AA or French sentences. High proficiency bilinguals could restrict selection to the target language regardless of the language context. In lower proficiency bilinguals, however, selection was specific to the target language in non-switching contexts but was nonspecific in switching contexts where cross-language interaction yielded inhibitory and facilitatory cognate effects. Results of this study therefore suggest that lexical selection in codeswitching bilinguals is dynamic and is dependent on proficiency, semantic constraints and language context. This within-subject study using auditory stimuli contributes towards a more ecological methodology in investigating sentence processing in codeswitching bilinguals.