A dynamic neural field model of asymmetric interference effects in code-switching

During instances of code-switching, bilingual speakers rapidly transition between languages. Following a transition from one language to the other, a code-switched word can exhibit phonetic differences from the same word produced in a single-language context. Observation of such ‘interference’ effects depends on language dominance. Interference effects are reported when a speaker switches from their non-dominant language into their dominant language, as shown, for example, in measurements of voice onset time (VOT) from Spanish-English bilinguals. We propose a neurocognitive model of such effects using Dynamic Field Theory (DFT). Interference arises from the interaction of separate language inputs into a single VOT planning field. Following principles from the inverse frequency effect, the amplitudes of the two language inputs are modulated by the frequency of language use, deriving the asymmetry. A key assumption underlying this result is that bilinguals’ speech representations interact in a shared phonetic space.