Cerebral mechanisms for suppression of inappropriate information during sentence comprehension.

In two experiments we investigated the extent to which interference from contextually inappropriate information was attenuated or suppressed over time in the two cerebral hemispheres during sentence comprehension. Subjects viewed centrally presented sentences ending in either a homophone or a homograph and made speeded judgments as to whether a laterally presented test word was related to the overall meaning of the sentence. Suppression of contextually inappropriate forms of homophones was found when test words were presented to either hemifield, but suppression of inappropriate senses of homographs was found only when test words were presented to the right visual hemifield. The results from the homograph experiment are consistent with the hypothesis that right and left hemisphere semantic selection systems operate in qualitatively different ways. The results from the homophone experiment suggest that while the left hemisphere may be more efficient at suppression, both hemispheres possess the ability to suppress inappropriate information to some degree.