Processing of Counterfactual Conditional Sentences with Differential Propositional Truth-Value in Mandarin Chinese: Evidence from ERP

Although many studies document the role of propositional truth-value in human psychological reading behavior, there is a relative paucity of research examining the role of differential propositional truth-value in processing Chinese counterfactual conditionals. This study is to investigate the role of differential propositional value in processing Chinese counterfactual conditionals by means of ERPs (event-related potentials). The study is based on comprehending two types of Chinese counterfactual conditionals, which is propositional truth value introduced by two different markers of conditional conjunctions in the protasis and apodosis, such as true counterfactual conditional markers jiaru (if) & jiu (so) in the sentence wo xiang yu jiaru you tui jiu keyi zai shuixia zhixi (I think if fish had legs so they could stifle under water), and false counterfactual conditional markers ruguo (if) & namo (then) in the sentence wo xiang gou ruguo you lin namo keyi zai shuixia huxi (I think if dogs had scales, then they could breathe under water). Two counterfactual propositional values (i.e. true and false propositional values) are constructed through manipulating sentence counterfactuality between the true and false counterfactual conditional markers in the protasis and the apodosis. Twenty-four full-time Chinese college students participated in the ERP study. The results demonstrated that processing the true counterfactual propositional sentences with conditional markers jiaru (if) & jiu (so) elicited the N400 effect relative to false propositional sentences with conditional markers ruguo (if) & namo (then). Moreover, the counterfactual sentences with true propositional conditions varied from the elicitation of the N400 effect in the protasis and absence of the N400 effect in the apodosis, showing that semantic roles may gradually disappear under the impact of truth value of propositional counterfactual condition, and/or the roles of semantic anomaly was eliminated in the accumulated sentence processing. While for the false counterfactual conditional sentences, elicitations of P300 in the protasis and robust N400 effect in the apodosis were shown, indicating the increasing semantic role in the processing. Interestingly, there was the absence of the P600 effect for processing sentences with syntactic violation, suggesting little extra syntactic cost in processing sentences with false propositional condition.