Unexpected words or unexpected languages? Two ERP effects of code-switching in naturalistic discourse

Understanding words in context: A naturalistic EEG study of children's lexical processing

When listening to speech, adults rely on context to anticipate upcoming words. Evidence for this comes from studies demonstrating that the N400, an event-related potential (ERP) that indexes ease of lexical-semantic processing, is influenced by the predictability of a word in context. We know far less about the role of context in children's speech comprehension. The present study explored lexical processing in adults and 5-10-year-old children as they listened to a story. ERPs time-locked to the onset of every word were recorded. Each content word was coded for frequency, semantic association, and predictability. In both children and adults, N400s reflect word predictability, even when controlling for frequency and semantic association. These findings suggest that both adults and children use top-down constraints from context to anticipate upcoming words when listening to stories.

Different language control mechanisms in comprehension and production: Evidence from paragraph reading

Chinese-English bilinguals read paragraphs with language switches using a rapid serial visual presentation paradigm silently while ERPs were measured (Experiment 1) or read them aloud (Experiment 2). Each paragraph was written in either Chinese or English with several function or content words switched to the other language. In Experiment 1, language switches elicited an early, long-lasting positivity when switching from the dominant language to the nondominant language, but when switching to the dominant language, the positivity started later, and was never larger than when switching to the nondominant language. In addition, switch effects on function words were not significantly larger than those on content words in any analyses. In Experiment 2, participants produced more cross-language intrusion errors when switching to the dominant than to the nondominant language, and more errors on function than content words. These results implicate different control mechanisms in bilingual language selection across comprehension and production.

The Effect of Code-Switching Experience on the Neural Response Elicited to a Sentential Code Switch

Switching between languages, or codeswitching, is a cognitive ability that multilinguals can perform with ease. This study investigates whether codeswitching during sentence reading affects early access to meaning, as indexed by the robust brain response called the N400. We hypothesize that the brain prioritizes the meaning of the word during comprehension with codeswitching costs emerging at a different stage of processing. Event-related potentials (ERPs) were recorded while Spanish-English balanced bilinguals (n = 24) read Spanish sentences containing a target noun that could create a semantic violation, codeswitch or both. Self-reported frequency of daily codeswitching was used as a regressor to determine if the cost of reading a switch is modulated by codeswitching experience. A robust N400 to semantic violations was followed by a late positive component (LPC). Codeswitches modulated the left anterior negativity (LAN) and LPC, but not the N400, with codeswitched semantic violations resulting in a sub-additive interaction. Codeswitching experience modulated the LPC, but not the N400. The results suggest that early access to semantic memory during comprehension happens independent of the language in which the words are presented. Codeswitching affects a separate stage of comprehension with switching experience modulating the brain's response to experiencing a language switch.