The N400’s broad sensitivity to meaningful stimuli and semantic manipulations meant that it could be used to ask questions about how meaning-related information is stored in the brain, in what is often called semantic memory (reviewed in Kutas & Van Petten 1994; Kutas & Federmeier 2000). These included studies of typicality and level of representation, of concreteness, and also of word type differences (e.g., nouns and verbs: Gomes et al 1997). At the most general level, two important findings cut across these studies. One was dissociation between RT and N400 measures, which only sometimes behaved similarly. Such dissociations are common to cognitive ERP measures, given that individual components reflect only a subset of the processes that contribute to RTs – and are, in fact, a useful dependent measure specifically for that reason. The other, perhaps more important, finding was that N400 data often did not fully support any of the available theories (even if ERP authors sometimes were compelled to choose a position), suggesting instead that aspects of each were correct. Consider, for example, the N400 work aimed at unearthing
