Electrophysiological evidence for the coexistence of expectancy fulfillment and semantic integration during the...

This study employed electrophysiological measures to investigate the processes of expectancy fulfillment and semantic integration during the processing of binding and compound nouns in Chinese. Sequential expectancy and cloze probability between the two constituents of a two-character noun were manipulated in two experiments, resulting in four types of target characters (i.e., the final characters of two-character nouns): (i) high-cloze, binding character (HB); (ii) high-cloze, compound character (HC); (iii) low-cloze, binding character (LB); (iv) low-cloze, compound character (LC). Participants were asked to judge as quickly and accurately as possible whether the two characters, presented sequentially, formed a real word. The two experiments varied in stimulus onset asynchrony (SOA) between the initial and the target characters: 1000 ms and 300 ms. ERPs acquired at the target characters revealed a significant semantic integration effect in both experiments whereby low-cloze target characters elicited more negative-going activities than high-cloze target characters (L > H) with both long and short SOAs. Importantly, there was a graded N400 effect (LC = LB > HC > HB) at the central region: a clearly visible positive deflection for HB relative to HC in synchrony with an equivalence in negativity for LB and LC. This graded pattern was observed with an SOA of 1000 ms but not 300 ms. These results are discussed in terms of the possible coexistence of an expectancy fulfillment mechanism indexed by the P300 that monitors incoming information for realization of expectancies based on stored mental representations and a semantic integration mechanism indexed by the N400 that incorporates incoming information into the preceding context based on semantic-pragmatic knowledge. Manifestation of this coexistence appears sensitive to SOA-modulated attention orientation.