Context Regularity Indexed by Auditory N1 and P2 Event-Related Potentials

It is still a question of debate whether the N1-P2 complex is an index of low-level auditory processes or whether it can capture higher-order information encoded in the immediate context. To address this issue, the current study examined the morphology of the N1-P2 complex as a function of context regularities instantiated at the sublexical level. We presented two types of speech targets in isolation and in contexts comprising sequences of Cantonese words sharing either the entire rime units or just the rime segments (thus lacking lexical tone consistency). Results revealed a pervasive yet unequal attenuation of the N1 and P2 components: The degree of N1 attenuation tended to decrease while that of P2 increased due to enhanced detectability of more regular speech patterns, as well as their enhanced predictability in the immediate context. The distinct behaviors of N1 and P2 event-related potentials could be explained by the influence of perceptual experience and the hierarchical encoding of context regularities.