Basque Center on Cognition, Brain and Language, Spain.
Cognition. 2012 Jan;122(1):102-9. doi: 10.1016/j.cognition.2011.09.001. Epub 2011 Oct 1.
Propositional truth-value can be a defining feature of a sentence's relevance to the unfolding discourse, and establishing propositional truth-value in context can be key to successful interpretation. In the current study, we investigate its role in the comprehension of counterfactual conditionals, which describe imaginary consequences of hypothetical events, and are thought to require keeping in mind both what is true and what is false. Pre-stored real-world knowledge may therefore intrude upon and delay counterfactual comprehension, which is predicted by some accounts of discourse comprehension, and has been observed during online comprehension. The impact of propositional truth-value may thus be delayed in counterfactual conditionals, as also claimed for sentences containing other types of logical operators (e.g., negation, scalar quantifiers). In an event-related potential (ERP) experiment, we investigated the impact of propositional truth-value when described consequences are both true and predictable given the counterfactual premise. False words elicited larger N400 ERPs than true words, in negated counterfactual sentences (e.g., "If N.A.S.A. had not developed its Apollo Project, the first country to land on the moon would have been Russia/America") and real-world sentences (e.g., "Because N.A.S.A. developed its Apollo Project, the first country to land on the moon was America/Russia") alike. These indistinguishable N400 effects of propositional truth-value, elicited by opposite word pairs, argue against disruptions by real-world knowledge during counterfactual comprehension, and suggest that incoming words are mapped onto the counterfactual context without any delay. Thus, provided a sufficiently constraining context, propositional truth-value rapidly impacts ongoing semantic processing, be the proposition factual or counterfactual.
命题真值可以成为句子与正在展开的话语相关性的一个决定性特征，而在上下文中确定命题真值则是成功解释的关键。在当前的研究中，我们调查了它在对反事实条件句理解中的作用，反事实条件句描述了假设事件的想象后果，并且被认为需要同时记住什么是真实的，什么是虚假的。因此，预先存储的现实世界知识可能会干扰并延迟反事实理解，这是一些话语理解理论所预测的，并且在在线理解中已经观察到了。命题真值的影响可能会在反事实条件句中延迟，这也被认为适用于包含其他类型逻辑运算符（例如否定、标量量词）的句子。在一项事件相关电位（ERP）实验中，我们研究了当描述的后果根据反事实前提都是真实且可预测时命题真值的影响。在被否定的反事实句子（例如，“如果美国宇航局没有开发其阿波罗计划，那么第一个登上月球的国家将是俄罗斯/美国”）和现实世界的句子（例如，“因为美国宇航局开发了其阿波罗计划，第一个登上月球的国家是美国/俄罗斯”）中，假词比真词引发了更大的 N400 ERP。这些由相反词对引起的、无法区分的命题真值的 N400 效应表明，在反事实理解过程中不会受到现实世界知识的干扰，并且表明输入的单词不会延迟地映射到反事实上下文中。因此，只要提供一个足够约束的上下文，命题真值就会迅速影响正在进行的语义处理，无论是事实命题还是反事实命题。
