Bilingual Flexibility: The Neurocognitive Basis of Language Control and Adaptation

• Applicant: Professor Dr. Stefan Heim
• Subject Area: General, Cognitive and Mathematical Psychology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548577702

Bilingual language use is characterised by flexibly switching between the mental lexica of different languages in response to situational requirements. To do so, the dispositional language balance of the bilingual speaker as a product of long-term adaptation over the lifespan must be temporarily modified in a given situation through processes of language control, resulting in a situational language balance. This project investigates the neurocognitive mechanisms of short-term, reactive, and medium-term, proactive, language control and adaptation processes. At the centre of the project, the neural basis of these behavioural effects of language control and adaptation is then investigated with task-based fMRI. We first look deeper into two established effects of language switching, N-2 Language Repetition Costs (reactive) and the Blocked Language Order Effect (proactive), in a series of behavioural experiments using language-cued picture naming tasks. We then go beyond the lexical level, investigating the cross-linguistic transfer of semantic-conceptual adaptation processes in language comprehension and production. Additionally, including questionnaire-based and performance-based measures of the speaker’s bilingual proficiency allows relating these short-term and medium-term effects of language control to the dispositional language balance of the speaker. Additional analysis of the functional (task-based and resting-state) and structural (DTI) connectivity allows describing the dynamic network architecture in the bilingual brain in terms of the interaction of dispositional and situational language balance and control. Thus, we contribute a neurocognitive framework of the relevant processes underlying bilingual flexibility to the Research Unit.

• DFG Programme: Research Units
• Subproject of: FOR 5905: Bilingual Flexibility – The Psychology of Language Control
• Co-Investigator: Professor Dr. Iring Koch