Investigation of code-switching cost in conversation and self-paced reading tasks

Aims and objectives: Studies of code-switching (CS) in bilingual speakers using laboratory tasks have been equivocal on whether CS is cognitively demanding. The goal of this study was to examine time costs at the juncture of a CS in a more ecologically valid experimental paradigm. Methodology: English (L1)–French (L2) bilingual speakers performed two tasks. The primary experimental task was a novel paradigm that elicited voluntary code-switches in conversation with a bilingual interlocutor. A silent self-paced reading task was used to compare with a laboratory task with involuntary switches. Data and analysis: Intersyllabic durations (conversation task) and reading times (reading task) were analyzed. CS cost was the time difference between code-switches and matched non-switches. Cost-switching costs for each switch direction (English-to-French and French-to-English) and type of switch (alternations and insertions) were also compared. Findings: Code-switches in conversation were associated with a time cost, and the magnitude was comparable in both directions although speakers more frequently switched from French-to-English. In self-paced reading, switching costs were observed only for switches into the dominant language. Across both tasks, there were no differences in CS time cost between insertions and alternations. Originality: This study reports a novel measure of CS costs in conversation, intersyllabic duration, and provides a cross-task comparison in the same group of bilingual speakers to better inform theories of CS. Implications: Bilingual speakers experience a time cost when making voluntary switches in conversations. The symmetrical switch costs suggest that both languages have similar activation levels throughout the conversation, and the cognitive costs arise from the act of momentarily switching languages, irrespective of their dominance. In self-paced reading, cognitive costs arise from disturbing the status quo of relative activation-inhibition of each language adopted to perform the task. The comparable CS time cost for insertions and alternations suggests similar cognitive control and linguistic planning mechanisms for both types of switches.

Language-switch costs from comprehension to production might just be task-switch costs

Spanish–English bilinguals switched between naming pictures in one language and either reading-aloud or semantically classifying written words in both languages. When switching between reading-aloud and picture-naming, bilinguals exhibited no language switch costs in picture-naming even though they produced overt language switches in speech. However, when switching between semantic classification and picture-naming, bilinguals, especially unbalanced bilinguals, exhibited switch costs in the dominant language and switch facilitation in the nondominant language even though they never switched languages overtly. These results reveal language switching across comprehension and production can be cost-free when the intention remains the same. Assuming switch costs at least partially reflect inhibition of the nontarget language, this implies such language control mechanisms are recruited only under demanding task conditions, especially for unbalanced bilinguals. These results provide striking demonstration of adaptive control mechanisms and call into question previous claims that language switch costs necessarily transfer from comprehension to production.

Individual differences in resilience to stress are associated with affective flexibility

Cognitive flexibility, the capacity to adjust behavior to changing situational demands, is frequently linked to resilience because of its important contribution to stress regulation. In this context, particularly affective flexibility, defined as the ability to flexibly attend and disengage from affective information, may play a significant role. However, there are so far only very few empirical investigations that directly explore the link between flexibility and resilience to stress. In the present study, the relationship of cognitive and affective flexibility and resilience was examined in 100 healthy participants. Resilience was measured with three self-report questionnaires, two defining resilience as a personality trait and one focusing on resilience as an outcome in the sense of stress coping abilities. Cognitive and affective flexibility were assessed in two experimental task switching paradigms with non-affective and affective materials and tasks, respectively. The cognitive flexibility paradigm additionally included measures of cognitive stability and dispositional cognitive flexibility. In the affective flexibility paradigm, we explicitly considered the affective valence of the stimuli before and during task switching. Response time switch costs in the affective flexibility paradigm were significantly correlated to all three self-report measures of resilience. Regarding the valence of the stimuli, the correlation with resilience was not specific to costs when switching from negative to positive information or vice versa. For cognitive (i.e., non-affective) flexibility, a significant correlation of response time switch costs was found with only one of the three resilience measures. A regression analysis including both affective and cognitive switch costs as predictors of resilience indicated that only affective, but not cognitive switch costs, explained unique variance components. Furthermore, the experimental measures of cognitive stability and dispositional cognitive flexibility did not correlate with resilience scores. These findings suggest that specifically the efficiency of flexibly switching between affective and non-affective information is related to resilience.

Do bilinguals outperform monolinguals in switching tasks? Contrary evidence for nonlinguistic and linguistic switching tasks

The benefits of bilingualism in executive functions are highly debated. Even so, in switching tasks, these effects seem robust, although smaller than initially thought (Gunnerud et al., 2020; Ware et al., 2020). By handling two languages throughout their lifespan, bilinguals appear to train their executive functions and show benefits in nonlinguistic switching tasks compared to monolinguals. Nevertheless, because bilinguals need to control for the interference of another language, they may show a disadvantage when dealing with task-switching paradigms requiring language control, particularly when those are performed in their less dominant language. The present work explored this issue by studying bilingualism’s effects on task-switching within the visual and language domains. On the one hand, our results show that bilinguals were overall faster and presented reduced switch costs compared to monolinguals when performing perceptual geometric judgments with no time for task preparation. On the other hand, no bilingual advantage was found when a new sample of comparable bilinguals and monolinguals completed a within-language switching task. Our results provide clear evidence favoring the bilingual advantage, yet only when the task imposes greater executive demands and does not involve language control.

Assessing the evidence for asymmetrical language switch costs and reversed language dominance effects - a meta analysis

Two seemingly counterintuitive phenomena – asymmetrical language switch costs and the reversed language dominance effect – prove to be particularly controversial in the literature on language control. Asymmetrical language switch costs refer to the larger costs for switching into the dominant language compared to switching into the less dominant language, both relative to staying in either one language. The reversed language dominance effect refers to longer reaction times when in the more dominant of the two languages in situations that require frequent language switching (i.e., mixed-language blocks). The asymmetrical language switch costs are commonly taken as an index for processes of transient, reactive inhibitory language control, whereas the reversed language dominance effect is taken as an index for sustained, proactive inhibitory language control. In the present meta-analysis, we set out to establish the empirical evidence for these two phenomena using a Bayesian linear mixed effects modelling approach. Despite the observation of both phenomena in some studies, our results suggest that overall, there is little evidence for the generality and robustness of these two effects, and this holds true even when conditions – such as language proficiency and preparation time manipulations – were included as moderators of these phenomena. We conclude that asymmetrical switch costs and the reversed language dominance effect are important for theory development, but their utility for theory testing is limited due to their lack of robustness and the absence of confirmed moderatory variables.

Predictions about the Cognitive Consequences of Language Switching on Executive Functioning Inspired by the Adaptive Control Hypothesis Fail More Often than Not

The adaptive control hypothesis developed by Green and Abutalebi is the most influential theory of bilingual language control. The focus of this article is on the predictions that other researchers have derived based on the three different modes of interactional context described by the hypothesis. Foremost, that dual-language contexts should enhance domain-general executive functions more than single-language contexts. Several recent and ambitious behavioral tests of these predictions are reviewed. Although there was some evidence that dual-language contexts are associated with smaller switch costs, the evidence is inconsistent and there were no similar advantages for inhibitory control. The hypothesis also predicts neuroanatomical adaptations to the three types of interactional context. A careful evaluation of the relevant fMRI and ERP studies that take into account whether behavioral differences align with neuroscience differences and resolves valence ambiguities led to the conclusion that the neuroscience evidence for the hypothesis is, at best, inconsistent. The study also includes new analyses of two large-sample studies that enable the identification of relatively pure cases of single-language bilinguals, dual-language bilinguals, and dense-code switchers. Across nine different measures of executive functioning, the predicted advantage of the dual-language context never materialized. The hypotheses derived from the adaptive control hypothesis do not accurately predict behavioral performance on tests of executive functioning and do not advance our understanding as to what dimensions of bilingualism may lead to enhancements in specific components of executive functioning.

Language Dominance and Sociolinguistic Experience Are Related to Language Control and Domain-General Monitoring Control: An Investigation in Bilinguals Who Live in a Minority/Majority Sociolinguistic Setting

Bilingual language control in production tasks with language switches is supposed to be linked to domain-general cognitive control. In the present study, we investigated the role of language dominance, measured on a continuous scale, in the relationship between measures of language control elicited through language switching in a picture naming task and non-linguistic cognitive control induced by stimulus-response interference in a Simon task. In our sample of bilinguals who speak both a minority and majority language (language pair of Uyghur-Chinese), the results showed that as bilinguals were more L2-dominant, a pattern of reversed asymmetry switch costs in language control, i.e., larger L2 than L1 switch costs, was observed. Furthermore, the findings showed that recent exposure to the L1 minority language was associated with the change in language switch costs in terms of both response latencies and accuracy rates. This suggests a role for sociolinguistic context in bilingual language control. Concerning cross-domain generality, globally sustained language control was found to be correlated with domain-general monitoring control in response latencies for all bilingual participants. It lends support to the idea that bilinguals tap into monitoring control in the context of language switching. Additionally, the cross-domain overlap was found between two non-equivalent measures (global language control vs. cognitive inhibitory control) in response latencies, specifically for L1-dominant bilinguals. This suggests that language dominance may have an impact on cross-domain generality in language-switching processes.

No need to choose: independent regulation of cognitive stability and flexibility challenges the stability-flexibility tradeoff

Adaptive behavior requires the ability to focus on a current task and protect it from distraction (cognitive stability) as well as the ability to rapidly switch to another task in light of changing circumstances (cognitive flexibility). Cognitive stability and flexibility have commonly been conceptualized as opposite endpoints on a stability-flexibility tradeoff continuum, implying an obligatory reciprocity between the two: greater flexibility necessitates less stability, and vice versa. Surprisingly, rigorous empirical tests of this critical assumption are lacking, however. Here, we tested this assumption by acquiring simultaneous measurements of cognitive stability (congruency effects) and flexibility (switch costs) while independently varying contextual demands on these functions with block-wise manipulations of the proportion of incongruent trials and task switches, respectively. If cognitive stability and flexibility are reciprocal, an increase in flexibility in response to higher switch rates should lead to a commensurate decrease in stability, and an increase in stability in response to more frequent incongruent trials should result in decreased flexibility. Across three experiments, using classic cued task switching (Experiments 1 and 3) and attentional set shifting (Experiment 2) protocols, we found robust evidence against an obligatory stability-flexibility tradeoff. Although we observed the expected contextual adaptation of stability and flexibility to changing demands, strategic adjustments in stability had no influence on flexibility, and vice versa. These results refute the long-held assumption of a stability-flexibility tradeoff, documenting instead that the cognitive processes mediating these functions can be regulated independently - it is possible to be both stable and flexible at the same time.