When case meets agreement: event-related potential effects for morphology-based conflict resolution in human language comprehension.

We present event-related potential evidence from language comprehension that processing conflicts arising from the same linguistic domain and appearing within the same time range do not interact when they draw upon distinct underlying neural populations. Thus, a combined violation of two morphosyntactic information types, number-agreement and case, engendered a LAN/N400-P600 pattern, while the corresponding single violations are associated with LAN-P600 and N400-P600 responses, respectively. The absence of an interaction between the two negativities indicates that neuronal resource sharing does not result from a similarity of function, but rather requires an overlap of the underlying neuronal populations.