The project BILBRAIN (Brain functional and anatomical correlates of variability in the degree of success in the learning of the L2 phonemes) used magnetic resonance imaging (MRI) to study functional, morphological and functional connectivity differences between good and poor perceivers of the L2. Data were collected from over 2 000 individuals using an online questionnaire about language history and relevant factors. Of these, 121 met the inclusion criteria: healthy Spanish (L1)-Catalan (L2) bilinguals who learned the L2 after the age of 4. The group was tested in three behavioural tasks designed to evaluate their ability to perceive the Catalan /e/-/ε/ vowel contrast that is very difficult for Spanish native speakers to discriminate. Twenty-seven performed below the native performance cut-off point, and were thus considered poor perceivers, while 16 performed as natives in all three tasks and were categorized as good perceivers. Altogether, 15 poor and 10 good perceivers have agreed to participate in the MRI study, with ongoing recruiting aiming to include 16 participants in each group. In the first study (session), two auditory functional MRI tasks were used to map the brain regions sustaining processes involved in phonological processing. Areas related to working memory were also be functionally defined. The second study explored if individual differences in learning of the L2 phonology can be explained by differences in how the speech-processing system modulates general cognitive processes. The aim was to investigate the interactions between speech-specific areas and memory areas during speech changes, compared to non-linguistic auditory changes. Study results shed light on the differences between good and poor perceivers in detecting phonological changes. In the third study, researchers investigated whether individual differences in the learning of the L2 phonology could be explained by differences in how the speech-processing system modulates auditory sensory structures. The focus was on the interactions between speech-specific cortical areas and the auditory thalamus during phonological processing, compared to voice processing on the same speech stimulus. Project work and findings advanced knowledge on how the brain processes and learns languages. The results also have the potential to facilitate development of efficient language teaching programmes.
Second language, phonemes, bilinguals, native speakers, phonological processing