Metamemory is crucial for monitoring, evaluating, and optimizing memory performance. The basis of metamemory, however, is a matter of considerable debate. In the present study, we examined the contribution of processing fluency-the ease of processing information during learning-to metamemory judgments. We recorded event-related potentials (ERPs) while participants studied related and unrelated word pairs across two study-test cycles in a judgment of learning (JOL) task. In the first study-test cycle, related pairs were associated with better cued recall, higher JOLs, and a reduced N400 amplitude than unrelated pairs. Crucially, between- and within subject correlational analyses indicated that reduced N400 amplitudes, indexing more fluent processing, were associated with higher JOLs. Furthermore, single-trial N400 mediated a small but significant portion of the relatedness effect on JOLs. In the second study-test cycle, relatedness still increased recall and JOLs. However, related and unrelated pairs did not differ in N400 amplitude. Rather, unrelated pairs elicited a parietal positivity in a later time window that partially mediated the relatedness effect on JOLs. Together, these results suggest that processing fluency, indexed by the N400, contributes to the relatedness effect on JOLs when novel word pairs are learned, but not when previously studied pairs are relearned. Our results also imply that aspects of fluency not captured by the N400 and/or explicit beliefs about memory contribute to JOLs. This study demonstrates the utility of ERPs in gaining new insights into the neurocognitive mechanisms of metamemory.

中文翻译：

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元记忆的神经认知基础：使用N400研究流利度对学习判断的贡献。

元内存对于监视，评估和优化内存性能至关重要。但是，元记忆的基础是一个颇有争议的问题。在本研究中，我们研究了处理流畅性的贡献（学习过程中处理信息的难易程度）到元记忆判断。我们记录了事件相关的电位（ERP），而参与者则通过学习判断（JOL）任务在两个学习测试周期中研究了相关和无关的单词对。在第一个研究测试周期中，相关的配对比不相关的配对具有更好的提示召回率，更高的JOL和N400振幅降低。至关重要的是，受试者之间和受试者之间的相关性分析表明，降低的N400振幅（索引更流畅的处理）与更高的JOL相关。此外，单次试验N400介导了对JOL的一小部分但重要的相关性影响。在第二个学习测试周期中，相关性仍然增加了回忆和JOL。但是，相关对和不相关对在N400幅度上没有差异。相反，不相关的对在以后的时间窗口中引起顶叶阳性，部分地介导了对JOL的相关性影响。总之，这些结果表明，当学习新颖的单词对时，由N400索引的处理流利性对JOL的关联性做出了贡献，但是当重新学习以前学习的单词对时，则没有。我们的结果还暗示，N400无法捕获的流畅性和/或关于内存的明确信念会助长JOL。这项研究证明了ERPs在获取元记忆的神经认知机制方面的新见解的实用性。