An alternative structure rescues failed semantics? Strong global expectancy reduces local-mismatch N400 in Chinese flexible structures

During comprehension of a hierarchical structure, semantic integration between sequential, mismatched sentential constituents does not proceed when the later word in the sequence (e.g., the noun in the verb + classifier + noun) can be assigned an alternative role in the sentence (e.g., as a modifier of a subsequent object noun) (Zhang et al., 2011). Using electrophysiological measures, we examined how the availability of an alternative structure and whether the reader is motivated to generate an alternative structure affect semantic integration in a hierarchical structure. The same set of sentences was employed in three experiments in which the semantic congruency between the adjective and the object noun in the local structure and the sentential-contextual expectancy towards a noun were manipulated simultaneously. The reader's motivation was manipulated by tasks in which they made semantic acceptability judgment (Experiment 1), passively viewed sentences for comprehension (Experiment 2), or actively predicted the upcoming word and monitored the compatibility between the anticipated and the actual input (Experiment 3). Stronger contextual expectancy reduced N400 responses to the object noun regardless of semantic congruency, indicating that strengthening the constraints of an alternative argument decreased the effort of semantic integration between incompatible local constituents. Relative to weaker expectancy, the incongruent noun preceded by a stronger expectancy context elicited reduced N400 responses when no active prediction was demanded but showed equal amplitudes when such a demand was high. These findings demonstrate that the semantic failure in a flexible structure is likely to be resolved by the comprehender's motivation to generate an alternative structure based on the active use of contextual expectancy information, thus highlighting the “role-dependent semantic processing” during sentence comprehension.