Hemispheric differences in perceptual integration during language comprehension: An ERP study

Abstract

The left hemisphere (LH) is responsible for many fundamental aspects of language; however, converging evidence suggests the right hemisphere (RH) is critically involved in higher-level language comprehension. We examined the extent of each hemispheres' access to a meaningful mental representation of language by recording electroencephalography while participants (N = 44) completed a computer-based task where auditory sentences described individual elements of an image. If integrated successfully, this allowed the construction of a meaningful mental representation. If unsuccessful, the individual elements were in themselves meaningless. Participants saw a lateralised image that was either an integrated representation of the object described in the previous auditory passage ("integrated"), an unintegrated representation of each of the individual elements ("unintegrated"), or an integrated representation of an object that did not match the previous passage ("unrelated"). Evidenced by the trend in N300 amplitudes, we found that both hemispheres accessed a mental representation that embodied the elements described in the preceding passage. However, only the RH distinguished integrated versus unintegrated targets, suggesting that the RH accessed a mental representation that embodied the correct spatial relationships between elements (i.e., perceptual integration) as well as the individual imagined elements (i.e., perceptual elaboration). These results provide evidence of a clear RH contribution to the integration of perceptual information during language comprehension.