Hemispheric differences in the processing of contextual information during language comprehension

This study investigated the proposition that the right hemisphere (RH) processes language in a global, integrative manner that maintains access to earlier contextual information, whereas the left hemisphere (LH) processes in a local fashion and only keeps active the most recent concept. Thirty-four right-handed participants completed a lexical decision task using a split visual-field paradigm, with reaction time and error rates recorded. Three sentences were presented, where an inference was required in order to produce coherence between the first and second sentences. The third sentence was not directly related to the inference generation, but was consistent with the scenario set out in the prior context. Targets were either "Global", where the target reflected the meaning of the inference generated in order for coherence to have been created; or "Local", where the target reflected the meaning of only the third sentence and therefore did not require integration of previous context. Significantly greater facilitation was observed for the RH/left visual field than LH/right visual field for "Global" targets, while no hemispheric differences were observed for "Local" targets. This study provides evidence for the distillation of current models of hemispheric language comprehension into underlying local and global processes.