The N400 Is Not a Semantic Anomaly Response: More Evidence from Adjective-noun Combination

Previous work has shown that the N400 ERP component is elicited by all words, whether presented in isolation or in structured contexts, and that its amplitude is modulated by semantic association and contextual predictability. Although these data suggest that the N400 reflects core semantic computations involved in processing any meaningful stimulus, the broader literature continues to maintain the alternative idea that the N400 response primarily indexes the recognition of semantic incongruity, in part because many designs have confounded predictability with congruity. In the current study, we evaluate the hypothesis that the N400 response indexes semantic anomaly with an adjective-noun paradigm that allows us to precisely control predictability through corpus counts. In three experiments, we find small and unreliable N400 effects of semantic congruity (yellow bag vs. innocent bag), and yet we find massive and reliable N400 effects of predictability (runny nose vs. dainty nose) under the same conditions. While these data alone cannot determine the functional interpretation of the N400 effect, they provide very clear evidence against the common characterization that ‘semantic anomaly’ is one of its primary determinants.