Hemispheric asymmetries in the resolution of lexical ambiguity

The linguistic phenomenon of lexical ambiguity has been intensively investigated as a means of gaining insight into general mechanisms of lexical access. It is now evident that both context and meaning frequency are significant factors in the determination of lexical outcomes. This suggests that hemispheric processes may be relevant to the resolution of lexical ambiguity, because both factors have been shown to have differential implications for the processing of language in the hemispheres. This study set out to examine the effects of context and meaning frequency on the resolution of ambiguous word meanings within the hemispheres. Sentences presented at the beginning of each trial embodied contexts which expressed either the dominant or subordinate meaning of a terminating homographic prime. Laterally presented target words reflected senses of the prime which were either consistent with, or inconsistent with, the context created by the preceding sentence. The most interesting results were observed at short prime-target intervals where it was found that although dominant meanings of the target did not give rise to visual field differences, subordinate meanings evoked facilitated responses only in the left visual field. This result suggests that the right hemisphere immediately and exhaustively activates the various meanings associated with a word, while in the left hemisphere initial access is selectively restricted to the dominant meaning. It is proposed that this reflects a model of language comprehension in which the right hemisphere plays a supportive role by making available a set of alternative and less probable word meanings, thus freeing the left hemisphere to focus cognitive resources upon the most probable meaning of a word in a given context.