Second Language Interferes with Word Production in Fluent Bilinguals: Brain Potential and Functional Imaging Evidence

TLDR

Bilingual individuals need effective mechanisms to prevent interference between their languages. The study aims to demonstrate phonological interference from the non‑target language in German‑Spanish bilinguals using ERPs and fMRI. Participants performed a picture‑naming task requiring speeded responses to the first letter of the target language name, with vowel/consonant cues and cross‑language response congruence manipulated, while the target language switched between blocks. Bilinguals exhibited greater phonological interference than monolinguals, reflected in slower responses, distinct ERP signatures, and increased left middle prefrontal cortex activation, indicating this region’s role in interference control.

Abstract

Abstract Bilingual individuals need effective mechanisms to prevent interference between their languages. Using event-related brain potentials (ERPs) and functional magnetic resonance imaging (fMRI), we present evidence for interference of phonological information from the nontarget language in German—Spanish bilinguals. A tacit picture-naming task was used in which bilinguals and monolinguals had to make speeded responses based on the first letter of the picture's name in the target language. In one condition, subjects were required to respond when the name began with a vowel and to withhold a response if it started with a consonant. Stimuli had been selected such that in half of the trials, the names in both languages necessitated the same response, whereas in the other half, responses were different for the two languages. For the bilinguals, the language in which the stimuli had to be named was changed after each block. Bilinguals showed phonological interference compared with monolingual performance, which was evident in their performance, ERPs, and fMRI patterns. Nonlanguage-specific brain areas such as the left middle prefrontal cortex were found to be crucial for the control of interference.