Control mechanisms in voluntary versus mandatory language switching: Evidence from ERPs

Cognitive and neural mechanisms of voluntary versus forced language switching in Chinese-English bilinguals: an fMRI study

The ecological validity of bilingual code-switching has garnered increasing attention in recent years. Contrary to traditional studies that have focused on forced language switching, emerging theories posit that voluntary switching may not incur such a cost. To test these claims and understand differences between forced and voluntary switching, the present study conducted a systematic comparison through both behavioral and neural perspectives. Utilizing fMRI alongside picture-naming tasks, our findings diverge from prior work. Voluntary language switching not only demonstrated switching costs at the behavioral level but also significantly activated brain regions associated with inhibitory control. Direct comparisons of voluntary and forced language switching revealed no significant behavioral differences in switching costs, and both shared several common brain regions that were activated. On the other hand, a nuanced difference between the two types of language switching was revealed by whole-brain analysis: voluntary switching engaged fewer language control regions than forced switching. These findings offer a comprehensive view of the neural and behavioral dynamics involved in bilingual language switching, challenging prior claims that voluntary switching imposes no behavioral or neural costs, and thus providing behavioral and neuroimaging evidence for the involvement of inhibitory control in voluntary language switching.

How processing emotion affects language control in bilinguals

Research has shown that several variables affect language control among bilingual speakers but the effect of affective processing remains unexplored. Chinese-English bilinguals participated in a novel prime-target language switching experiment in which they first judged the affective valence (i.e., positive or negative) of auditorily presented words and then named pictures with neutral emotional valence in either the same (non-switch trial) or different language (switch trial). Brain activity was monitored using functional magnetic resonance imaging (fMRI). The behavioral performance showed that the typical switch cost (i.e., the calculated difference between switch and non-switch trials) emerged after processing positive words but not after negative words. Brain imaging demonstrated that processing negative words immediately before non-switch picturing naming trials (but not for switch trials) increased activation in brain areas associated with domain-general cognitive control. The opposite patterns were found after processing positive words. These findings suggest that an (emotional) negative priming effect is induced by spontaneous exposure to negative words and that these priming effects may be triggered by reactive emotional processing and that they may interact with higher level cognitive functions.

Cost or advantage? Intra-sentential language switching could facilitate L2 emotional words' comprehension in auditory modality

Language switching is encountered commonly and inevitably in bilingual society and often induces costs for target language's production. However, for auditory words' comprehension at sentence level, the limited research showed divergent findings. Some research observed comprehension costs when the language of target words was switched with the code of sentential contexts kept constant; but a potential switch advantage was also showed in non-dominant targets' processing when sentential context switches occurred. Additionally, it's well documented that the words' emotional connotations play a key role in both L1 and L2 word comprehension. Therefore, we aimed to explore which switch effect would occur when bilinguals comprehended L1/L2 emotional target nouns in auditory modality at behavioral and neural level through a visual object selection task. Behaviorally, switch related costs occurred in L1 targets' comprehension, whereas advantage effects were found in L2. Moreover, greater switch advantage occurred for positive and negative targets than for neutral ones. Consistently, larger LPC (Late Positive Component) defection was elicited for L2-Switch trials relative to L2-Nonswitch trials and the differences of LPC's amplitude could predict the behavioral advantageous effects of switching in nondominant targets' comprehension, which suggest that language switching lead to deeper re-analyses for emotional words. Taken together, it's suggested that bilinguals can adaptively utilize top-down (sentential prediction) and bottom-up (words' emotional information) cues to access weaker L2 representations.

When interlocutor's face-language matching alters: An ERP study on face contexts and bilingual language control in mixed-language picture naming

The present study used event-related potentials (ERP) to examine Chinese-English bilinguals' reactive and proactive language control as they performed mixed-language picture naming with face cues. All participants named pictures in Chinese (first language, L1) and English (second language, L2) across three sessions: a 25% face-language matched session, a baseline session without face cues, and a 75% face-language matched session. Behavioral analyses for reactive language control showed that the asymmetrical switch cost was larger for L2 than L1 in the 25% session and for L1 than L2 in the 75% session. ERP results revealed more negative N2 and LPC during L1 switching in 25% session but enhanced N2 during L2 switching in 75% session. Similar N2 and LPC effect was found during L1 and L2 switching in the baseline context. For proactive language control, the reversed language dominance and enhanced LPC amplitudes during L2 naming were consistent across the three sessions. Our findings suggest that reactive but not proactive language control is modulated by the ever-changing face contexts, which highlights the highly flexible bilingual control systems subserving nonlinguistic cues.

The Role of Language Switching During Cross-Talk Between Bilingual Language Control and Domain-General Conflict Monitoring

The relationship between bilingual language control and executive control is debated. The present study investigated the effect of short-term language switching in a comprehension task on executive control performance in unbalanced bilinguals. Participants were required to perform a context task and an executive control task (i.e., flanker task) in sequence. A picture-word matching task created different language contexts in Experiment 1 (i.e., L1, L2, and dual-language contexts). By modifying the color-shape switching task, we created different contexts that do not involve language processing in Experiment 2 (i.e., color, shape, and dual context). Experiment 1 showed overall faster responses (in both congruent and incongruent trials) in the flanker task after a language switching context than after single (L1 or L2) contexts. This suggests that the language switching in a comprehension task affected general monitoring performance. By contrast, the nonlinguistic contexts in Experiment 2 did not affect flanker performance. This provides further evidence for the crucial role of language processing during switching to elicit short-term adaptions on domain-general conflict monitoring. Overall, our findings add to the previous studies by showing cross-talk between bilingual language control and domain-general conflict monitoring when language switching occurs in a comprehension task.