Brain responses to semantic incongruity in bilinguals.

Event-related potentials were examined in the first and second languages of bilinguals, and in monolinguals. Stimuli were anomalous sentences presented one word at a time on a CRT monitor. The principal dependent measure was the N400 component, and an accompanying frontal negativity, which provided an estimate of the amount of time the nervous system takes to determine the semantic incongruity of a given word. The results indicate that N400 latency is slightly, but significantly, delayed in bilinguals, with monolinguals having the shortest mean N400 latency, the first language of bilinguals next, and the second language of bilinguals longest. The frontal negativity varied in amplitude somewhat independently of the parietal N400. The amplitude of the frontal negativity was sometimes reduced in the second language, tending to be smaller in those subjects who used their second language the least. Neither N400 nor the frontal negativity varied as a function of age of acquisition of the second language. The results are discussed with reference to the relative automaticity of language in bilinguals, and the sensitivity of N400 to variations in the automaticity of language processing.