The sensitivity of the right hemisphere to contextual information in sentences

One explanation for the inconsistencies in research examining the sentence comprehension abilities of the right hemisphere (RH) is the presence of confounding variables that have generally served to disadvantage the processing capacities of the RH. As such, the present study aimed to investigate hemispheric differences in the use of message-level sentential information by removing some of the factors known to be inherently disadvantageous for RH comprehension. Thirty-two right-handed undergraduate university students participated in a computer-based lexical decision task where RT and error rates were recorded. The sensitivity of each hemisphere to the message-level contextual information contained in short versus long sentences was compared, as well as the effect of stimulus modality (visual compared to auditory). The results showed that the RH benefited from increased levels of context to at least the same extent as the LH and that, more importantly, this could not be explained by word-level processes alone. This finding, unusual in behavioral research on normal individuals but consistent with neuropsychological, electrophysiological, and neuroimaging approaches, suggests that the RH plays an important role in sentence comprehension, at least in relation to sentences that conform to a relatively simple structure.