Despite evidence to the contrary, the N400 has long been thought of as a “language” measure. As we hope to make clear, it is much more than that – however, it is true that the N400 is a particularly powerful tool for studying language. The N400 opened the door to investigation of the neural bases of language comprehension in the normal population, not just individuals with aphasia. By neural basis we mean characterization of the neural representations and functions supporting language processing not localization of those functions. Interest in neural basis aside, the observed systematicity between sensory, conceptual, and linguistic factors and properties of the N400 (together with those of ERPs more generally) have made it amenable for addressing core psycholinguistic questions that had proven intractable to most other dependent measures.
