Sitting on the fence: An EEG investigation of the role of the right hemisphere in metaphor processing

Studies of brain damaged and healthy individuals have pointed to a special role for the right cerebral hemisphere in processing metaphor. The present study focused on the processing of single word metaphors (i.e., metaphoric polysemy). EEG methodology was used to measure brain responses in a single word priming paradigm with a lexical decision task on the target.

Visually displayed metaphorical words were used as primes followed 750 ms later by literal, metaphoric or unrelated targets. Analysis was based on recordings from twenty healthy subjects, each exposed to thirty repetitions of each condition. Reductions of the N400 component in graphical representations of the ERPs and mean ERP potentials indicate priming of both the literal and the metaphorical targets with greater priming for the metaphorical target in the right than left hemisphere, in conformity with the theory of a special role for the right hemisphere in metaphor processing. However, repeated measures ANOVAs did not reveal statistically significant differences between the cerebral hemispheres, and so the findings of this study provide no conclusive evidence for a special role for the right hemisphere in processing metaphor. Further testing using a refined technique and measures to reduce noise may in future allow better understanding of metaphor processing.

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