Cognitive conflict and inhibition in primed dichotic listening.

In previous behavioral studies, a prime syllable was presented just prior to a dichotic syllable pair, with instructions to ignore the prime and report one syllable from the dichotic pair. When the prime matched one of the syllables in the dichotic pair, response selection was biased towards selecting the unprimed target. The suggested mechanism was that the prime was inhibited to reduce conflict between task-irrelevant prime processing and task-relevant dichotic target processing, and a residual effect of the prime inhibition biased the resolution of the conflict between the two targets. The current experiment repeated the primed dichotic listening task in an event-related fMRI setting. The fMRI data showed that when the task-irrelevant prime matched the task-relevant targets, activations in posterior medial frontal cortex (pMFC) and in right inferior frontal gyrus (IFG) increased, which was considered to represent conflict and inhibition, respectively. Further, matching trials where the unprimed target was selected showed activation in right IFG, while matching trials where the primed target was selected showed activations in pMFC and left IFG, indicating the difference between inhibition-biased selection and unbiased selection.