Whole-Language and Item-Specific Inhibition in Bilingual Language Switching: The Role of Domain–General Inhibitory Control

Abstract

A prominent theory of bilingual speech production holds that appropriate language selection is achieved via inhibitory control. Such inhibition may operate on the whole-language and/or item-specific level. In this study, we examined these two levels of control in parallel, by introducing a novel element into the traditional cued language switching paradigm: half of the stimuli were univalent (each required naming in the same language every time it appeared), and the other half were bivalent (each required naming in different languages on different trials). Contrasting switch and stay trials provided an index for whole-language inhibition, while contrasting bivalent and univalent stimuli provided an index for item-specific inhibition. We then investigated the involvement of domain-general brain mechanisms in these two levels of language control. Neuroimaging studies report activation of the pre-supplementary motor area (pre-SMA), a key region in the executive control brain network, during language switching tasks. However, it is unclear whether or not the pre-SMA plays a causal role in language control, and at which level it exerts control. Using repetitive transcranial magnetic stimulation (TMS) to transiently disrupt the pre-SMA, we observed an essential role of this brain region in general speech execution, while evidence for its specific involvement in each level of inhibition remains inconclusive.

The concept of inhibition in bilingual control.

“…Hence, by having a relatively higher selection threshold for L1 than L2, a reversed language dominance pattern should be observed. Though, since Costa and Santesteban (2004) assumed that only highly proficient bilinguals are able to change the selection thresholds for each language, a reversed language dominance pattern should only be observed with highly proficient bilinguals, which does not seem to be the case (e.g., Costa & Santesteban, 2004, Experiment 1; Liu et al, 2016; Zhu & Sowman, 2020). Therefore, the assumption that language proficiency is a major factor in the occurrence/absence of the reversed language dominance effect, as suggested by Costa and Santesteban (2004), seems unlikely.…”

Bilingualism and Aging: Implications for (Delaying) Neurocognitive Decline

“…As we move toward harnessing the insights for application/intervention from the basic science research looking into potential connections between bilingualism and cognitive aging, research that employs other methods, such as Trancranial direct current stimulation (tDCS) and/or Transcranial magnetic Stimulation (TMS), are also welcome. While these methods have both basic science application and therapeutic potential, especially as paired with cognitive training for the functional connectivity of working memory in the elderly (Nissim et al, 2019;Indahlastari et al, 2021), and although they have been used in bilingual language control research showing some promising effects in studies focusing on younger bilinguals (Hämäläinen et al, 2018;Radman et al, 2018;Jost et al, 2020;Tong et al, 2020;Zhu and Sowman, 2020;Vaughn et al, 2021), these methods are virtually unknown in the literature on bilingualism and cognitive aging.…”

The impact of cues on language switching: do spoken questions reduce the need for bilingual language control?

“…We predict that auditory cues like 'say' used by Hernandez and colleagues (1999Hernandez and colleagues ( , 2000Hernandez and colleagues ( , 2001 similarly activate the speech goal as question cues used in the present study and by (Tarlowski et al, 2013). To understand whether speech production in response to an auditory cues is crucial to capture BLC, the auditory questions could be compared to visual questions as used by Zhu and Sowman (2020). Furthermore, to understand whether a communicative cue, like a question or the word 'say', has an additional benefit over non-communicative words could be tested by comparing…”