The mechanisms and the scope of bilingual language production

When bilinguals plan to speak even one word, lexicalization processes of the two languages becomes concurrently activated. Surprisingly, bilingual speech production is not dramatically affected. This observation raises the questions about the control mechanisms that ensure lexicalization in the intended language and their representational scope. The aim of this dissertation was to increment the general knowledge on these two aspects of bilingual language control. To do so, we measured behavioral, electrophysiological, and neural responses in language switching tasks to investigate the mechanisms and the scope of bilingual language control. Moreover, we measured behavioral and neural responses in linguistic and non-linguistic switching tasks to explore the overlap between bilingual language control and domain-general executive control. The most consistent findings of this dissertation suggest that the mechanisms of bilingual language control are different from domain-general inhibitory control and that they are applied globally on the dominant language and likely also locally on the non-dominant language. The evidence presented in the current dissertation not only extends previous knowledge on bilingual language control, but it also provides a clearer understanding of the role of inhibitory control in switching tasks, an information relevant for any model of bilingual language control.En el momento que los bilingües planean hablar, incluso si es sólo una palabra, los procesos de lexicalización se activan simultáneamente en ambas las lenguas. Sorprendentemente, la producción del habla bilingüe no se ve afectada de forma significativa. Esta observación plantea preguntas acerca de los mecanismos de control que garantizan la lexicalización en la lengua deseada así como su alcance. Esta tesis tiene como objetivo incrementar el conocimiento general sobre estos dos aspectos de control lingüístico en los bilingües. Para ello, en diferentes experimentos se midieron respuestas conductuales, electrofisiológicas y neuronales en tareas de cambio lingüísticas para investigar los mecanismos y el alcance del control de las lenguas. Además, se midieron las respuestas conductuales y neuronales en tareas de cambio lingüísticas y no lingüísticas para explorar el solapamiento entre el control lingüístico y el control ejecutivo de dominio general. Los hallazgos más consistentes de esta tesis sugieren que los mecanismos de control lingüístico en los bilingües son diferentes de control inhibitorio de dominio general y que se aplican a nivel global en la lengua dominante y probablemente también a nivel local en la lengua no dominante. La evidencia aportada en esta tesis no sólo extiende el conocimiento previo sobre el control lingüístico en los bilingües, sino que además proporciona una comprensión más clara sobre el papel del control inhibitorio en las tareas de cambio, una información relevante para cualquier modelo de control lingüístico bilingüe

A multiple-choice task with changes of mind

The role of changes of mind and multiple choices has recently received increased attention in the study of perceptual/ndecision-making. Previously, these extensions to standard two-alternative tasks have been studied separately. Here we/nexplored how changes of mind depend on the number of choice-alternatives. To this end, we tested 14 human subjects on/na 2- and 4-alternative direction-discrimination task. Changes of mind in the participants’ movement trajectories could be/nobserved for two and for four choice alternatives. With fewer alternatives, participants responded faster and more/naccurately. The frequency of changes of mind, however, did not significantly differ for the different numbers of choice/nalternatives. Nevertheless, mind-changing improved the participants’ final performance, particularly for intermediate/ndifficulty levels, in both experimental conditions. Moreover, the mean reaction times of individual participants were/nnegatively correlated with their overall tendency to make changes of mind. We further reproduced these findings with a/nmulti-alternative attractor model for decision-making, while a simple race model could not account for the experimental/ndata. Our experiment, combined with the theoretical models allowed us to shed light on: (1) the differences in choice/nbehavior between two and four alternatives, (2) the differences between the data of our human subjects and previous/nmonkey data, (3) individual differences between participants, and (4) the inhibitory interaction between neural/nrepresentations of choice alternatives.This work was supported by the “CONSOLIDER-INGENIO 2010” Programme in the “Brainglot” project (Bilingualism and Cognitive Neuroscience) CSD2007-00012. FMB was supported by a predoctoral fellowship from the Spanish Government (FPU 2009-2013). GD was further supported by the Spanish Ministry of Science in the project “Communication and Information Processing Between Cortical Circuits: Oscillations and Plasticity” SAF2010-16085. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Qualitative differences between bilingual language control and executive control: evidence from task-switching

Previous research has shown that highly proficient bilinguals have comparable switch costs in both directions when they switch between languages (L1 and L2), the so-called "symmetrical switch cost" effect. Interestingly, the same symmetry is also present when they switch between L1 and a much weaker L3. These findings suggest that highly proficient bilinguals develop a language control system that seems to be insensitive to language proficiency. In the present study, we explore whether the pattern of symmetrical switch costs in language switching tasks generalizes to a non-linguistic switching task in the same group of highly proficient bilinguals. The end goal of this is to assess whether bilingual language control (bLC) can be considered as subsidiary to domain-general executive control (EC). We tested highly proficient Catalan-Spanish bilinguals both in a linguistic switching task and in a non-linguistic switching task. In the linguistic task, participants named pictures in L1 and L2 (Experiment 1) or L3 (Experiment 2) depending on a cue presented with the picture (a flag). In the non-linguistic task, the same participants had to switch between two card sorting rule-sets (color and shape). Overall, participants showed symmetrical switch costs in the linguistic switching task, but not in the non-linguistic switching task. In a further analysis, we observed that in the linguistic switching task the asymmetry of the switch costs changed across blocks, while in the non-linguistic switching task an asymmetrical switch cost was observed throughout the task. The observation of different patterns of switch costs in the linguistic and the non-linguistic switching tasks suggest that the bLC system is not completely subsidiary to the domain-general EC system.This work was supported by grants from the Spanish government (PSI2008-01191, Consolider Ingenio 2010 CSD2007-00012) and the Catalan government (ConsolidatSGR2009-1521)./nMarco Calabria was supported by a postdoctoral fellowship from the Spanish Government (Juan de la Cierva fellowship). Francesca M. Branzi was supported by a predoctoral fellowship from the Spanish Government (FPU-2009-2013). This research was also supported by a Marie Curie International Outgoing Fellowship within the seventh European Community Framework Programme awarded to Mireia Hernández

On the overlap between bilingual language control and domain-general executive control

We explored the overlap between bilingual language control (bLC) and domain-general executive control (EC) by focusing on inhibitory control processes. We tested 62 bilinguals in linguistic and non-linguistic switching tasks for two types of costs, such as the n − 1 shift cost and the n − 2 repetition cost. In order to explore the involvement of inhibitory control in bLC and EC, we assessed the pattern of switch costs in the two tasks and then we correlated them between tasks. Results showed reduced n − 2 repetition costs as compared to n − 1 shift costs in the linguistic task only, suggesting that small amount of inhibition were deployed when switching between languages. Importantly, neither the n − 1 shift costs nor the n − 2 repetition costs were correlated between tasks. These results, supported by additional evidence from the ex-Gaussian analysis, suggest that inhibitory control is differently involved in bLC and in EC.This work was supported by grants from the Spanish Government (PSI2014-54500, PSI2008-01191, PSI2011-23033, PSI2011-23340, Consolider Ingenio2010 CSD2007-00012), the Catalan Government (Consolidat SGR 2009-1521and SGR 2014-1210) and by one grant from the European Research Council under the European Community’s Seventh Framework (FP7/2007-2013 Cooperation grant agreement 613465-AThEME). This research received partial financial assistance as a Severo Ochoa Center of ExcellenceSEV-2015-0490. Francesca M. Branzi was supported by a predoctoral fellowship from the Spanish Government (FPU-2009-2013) and by a postdoctoral fellowship from the European Union’s Horizon 2020 research and innovation programme, under the Marie Sklodowska-Curie grant agreement No 658341. Marco Calabria was supported by a postdoctoral fellowship from the Spanish Government (Ramón y Cajal Fellowship)

On the reliability of switching costs across time and domains

Bilingual speakers are suggested to use control processes to avoid linguistic interference from the unintended language. It is debated whether these bilingual language control (BLC) processes are an instantiation of the more domain-general executive control (EC) processes. Previous studies inconsistently report correlations between measures of linguistic and non-linguistic control in bilinguals. In the present study, we investigate the extent to which there is cross-talk between these two domains of control for two switch costs, namely the n-1 shift cost and the n-2 repetition cost. Also, we address an important problem, namely the reliability of the measures used to investigate cross-talk. If the reliability of a measure is low, then these measures are ill-suited to test cross-talk between domains through correlations. We asked participants to perform both a linguistic- and non-linguistic switching task at two sessions about a week apart. The results show a dissociation between the two types of switch costs. Regarding test–retest reliability, we found a stronger reliability for the n-1 shift cost compared to the n-2 repetition cost within both domains as measured by correlations across sessions. This suggests the n-1 shift cost is more suitable to explore cross-talk of BLC and EC. Next, we do find cross-talk for the n-1 shift cost as demonstrated by a significant cross-domain correlation. This suggests that there are at least some shared processes in the linguistic and non-linguistic task.The research leading to these results has received funding from the Dutch Organization for Scientific Research (NWO) with grant 446-14-006 and from the Ministerio de Economía, Industria y Competitividad (MINECO) with the Juan de la Cierva grant (IJCI-2016-28564) awarded to KT. This work was also supported by grants from the Spanish government (PSI2014-52181-P and PSI2017-87784-R), the Catalan government (SGR 2009-1521 and 2017 SGR 268), the La Marató de TV3 Foundation (373/C/2014), and the European Research Council under the European Community’s Seventh Framework (FP7/2007–2013 Cooperation Grant Agreement 613465-AThEME). And last, MC was supported by the postdoctoral Ramón y Cajal fellowship (RYC-2013-14013) and FB was supported by the postdoctoral Marie Sklodowska-Curie fellowship (658341)