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Individual Differences Shape ERP Responses to Bilingual Code-Switched Sentences
Poster Session B, Friday, September 12, 4:30 - 6:00 pm, Field House
Yun (Ingrid) Chuang1, Janet G. van Hell1; 1The Pennsylvania State University
Bilinguals often switch between languages within a single utterance—a phenomenon known as code switching, which offers a powerful lens for examining cross language interaction and the cognitive control mechanisms engaged during comprehension. Prior auditory ERP research (Fernandez, Litcofsky, & Van Hell, 2019) revealed that bilinguals’ listening to sentences that switched from their dominant to their weaker language elicited an N400 effect (semantic access) followed by an LPC effect (sentence level reanalysis), whereas switches from the weaker to the dominant language elicited only an N400 effect. While these and related findings highlight different neural responses for the two code-switching directions at the group level (for review, see Van Hell, 2022), the extent to which individual cognitive and linguistic profiles shape these neural responses remains underexplored. This study examined how individual differences in language proficiency, cognitive control, and familial sinistrality shape ERP responses to code switched sentence comprehension Forty-four native Spanish speakers highly proficient in English listened to 160 sentences across four conditions: English only, English to Spanish switches, Spanish only, and Spanish to English switches. EEG was recorded while participants completed the task. We assessed Spanish and English proficiency with the MINT, cognitive control via the AX CPT task, and familial sinistrality through a handedness inventory. ERP responses were analyzed in the N400 (300–500 ms) and LPC (500–900 ms) windows using linear mixed-effects models. At the group level, results replicated prior findings (Fernandez et al., 2019): dominant-to-weaker switches elicited both N400 and LPC effects, while weaker-to-dominant switches showed only N400 responses. This indicates that both switch directions involve lexical access challenges, but only dominant-to-weaker switches require additional sentence-level integration. Crucially, individual differences modulated these effects. Higher dominant-language proficiency was linked to smaller N400 amplitudes and larger LPC effects during dominant-to-weaker switches, as well as reduced N400 amplitudes for weaker-to-dominant switches. These results suggest that stronger dominant-language skills help facilitate meaning access, but requires continued integration in dominant-to-weaker switches. It also enhances efficient lexical access in weaker-to-dominant switches. In contrast, higher weaker-language proficiency was associated with larger N400 amplitudes during dominant-to-weaker switches but did not affect responses in the other direction. This pattern indicates that individuals with stronger weaker-language skills engage in deeper semantic processing when switching from their dominant to weaker language. Participants with stronger cognitive control showed reduced N400 amplitudes in both switching directions, suggesting that better regulation supports more efficient processing across language boundaries. In addition, participants with a familial sinistrality background exhibited smaller LPC effects and larger N400 amplitudes during dominant-to-weaker switches, and larger N400s during weaker-to-dominant switches. This pattern is consistent with prior research showing that individuals with familial sinistrality tend to focus more on lexical-level meaning than sentence-level integration (Lee, 2018). Together, these findings reveal that individual differences in linguistics skills, cognitive control and familial sinistrality shape the neural mechanisms underlying code-switched sentence comprehension. They highlight the importance of moving beyond group-level analyses to understand how bilingual listeners manage code-switches in real time.
Topic Areas: Multilingualism, Control, Selection, and Executive Processes