[Interaural attention switching suppresses N400 attenuation with spoken word repetition]

Event-related brain potentials were recorded from participants who listened to two pairs of words (and occasionally nonwords) simultaneously presented to both ears with stimulus onset asynchrony (SOA) of 1 s on a trial. When participants were instructed to fixate their attention to one ear and detect nonwords, the N400 attenuation was observed for a word repeated in the attended ear. The requirement of interaural attention switching between the first and second presentations of word pairs, however, suppressed the repetition effect on N400, even when the first and repeated presentations of a word were attended. The suppression of N400 attenuation was interpreted to indicate that attention switching interferes with the immediate availability of the decision for the first presentation in working memory.