知道感（FOK）和不知道感（FOnK）的双向实验分离

为了实现FOK（feeling-of-knowing）和FonK（feeling-of-not-knowing）的双向分离，实验一采用高频词或者低频词为线索项目，检验FOK和FOnK的预测准确性。结果发现，在低频线索条件下FOK的预测准确性表现出高于FOnK的预测准确性的趋势，而在高频线索条件下则正好相反，但上述两组差异并未在统计学上达到显著的程度。实验二采用词－非词对和相关词对两种实验条件，在证明相关词对条件可以促进FOK并降低FOnK的同时，观察到词－非词条件可以促进FOnK并降低FOK，从而在较为严格的意义上证明了FOK和FOnK是两个不同的维度的量。上述结果为知道感的“双过程假设”提供了进一步的实验证据

Double Dissociation between Feeling-Of-Knowing (FOK) and Feeling-of-not-Knowing (FOnK)

People can still have a feel of “I know that”, even though they cannot retrieve the target information. This phenomenon is known as FOK (feeling-of-knowing). Although almost all theories on FOK assume it to be a continuum of subjective feeling from weak to strong, recent neuroimaging studies implied ‘feeling-of-knowing’ (FOK) and ‘feeling-of-not-knowing’ (FOnK) might be sub-served by different cognitive and neural processes (Luo et al., 2002; Luo et al., 2003；Luo et al., 2004). This dual processes hypothesis challenges the traditional view on FOK and provided a new perspective for investigation. In our previous study, we have examined the effects of level-of-processing (LOP) on FOK and FOnK respectively. The results showed that deep LOP promoted the predictive accuracy of FOK, but not that of FOnK. Moreover, deep LOP deteriorated the predictive accuracy of FOnK. In this study, we attempted to get double dissociation evidence for this dual processes hypothesis of FOK. We compared the predictive accuracy of FOK and FOnK when the cue items were low- or high-frequency words (Experiment 1) or when the materials were “word”-“word” pairs or “word”-“non-word” pairs (Experiment 2). Method Sixty paid volunteers participated in the study (30 in each experiment). In the Recall-Judgment-Recognition (RJR) procedure, participants first learned a list of cue-target pairs. They were then provided with the cue items one by one and were asked to retrieve the corresponding target items. If failed, they were asked to make a feeling-of-knowing judgment or a feeling-of-not-knowing (the cued-recall &; FOK judgment stage). Finally, participants were given a criterion recognition test to examine if their metamemory prediction was accurate or not (the recognition stage). Based on the performance in the cued-recall &; FOK judgment stage and the recognition stage, the items were sorting into five types: SC, PP, NP, PN, and NN: cue-recall and FOK judgment Successful cue-recall Failing cue-recall positive judgment negative judgment recognize Hint SC PP NP error report PN NN The predictive accuracy of FOK (PA-FOK) and that of FOnK (PA-FOnK) were estimated as follows: PA-FOK ＝ PP / PP+PN PA-FOnK ＝ NN / NN+NP Results The result of Experiment 1 showed, in low-frequency cue words condition, the accuracy of FOK tended to be higher than that of FOnK, whereas in the high-frequency cue words condition, the reverse tendency was observed. However, these differences did not achieve significant level. The result of Experiment 2 showed, in the “word”-“word” condition, the accuracy of FOK was significantly higher than that of FOnK, whereas in the “word”-“non-word” condition, the accuracy of FOK was significantly lower than that of FOnK. This observation showed the double dissociation of FOK and FOnK. Conclusions This study suggests that the FOK and FOnK can be doubly dissociated. Some variables can promote the predictive accuracy of FOK but deteriorate that of FOnK, whereas other variables can have the reverse effects: they promote FOnK but deteriorate FOK. Based on these evidences, together with previous neuroimaging studies, we suggested that FOK and FOnK are supported by distinct cognitive brain processes