The fact that N400s could be observed for both visual and auditory words afforded cross-modality comparisons that were relatively less tractable for RT studies. The functional similarity of the N400 generating process in the two modalities (e.g., sensitivity to semantic relations, sentential congruity, and related anomaly effects – N400 reductions to anomalous words semantically related to the highest cloze endings for a sentence frame) was theoretically important for psycholinguistics, making the occasional differences and interactions all the more notable. Auditory N400s tended to begin earlier (although not when speech was presented at a fixed rate, as in the visual modality, rather than naturally), last longer, and have a slightly more frontal and less right-biased topography (reviewed in Kutas & Van Petten 1994). Finding different patterns of N400 effects (across SOA) when the prime was an auditory word and the target a visual word or vice versa, Holcomb and Anderson (1993) argued for an amodal semantic system tapped by modality specific processes. Importantly, however, the modality general aspects of the N400 effects made it easier to investigate language representations and process
