Sensitivity of item memory to fluency: Evidence from behavioral data and ERP old/new effects

Background: Previous studies have suggested that item memory is processed based on both familiarity and recollection, and evidence can be found from behavioral as well as event-related potential (ERP) patterns. Recently, great consideration has been given to how the memory of items generated from internal and external sources differ from each other. To date, the modulation of fluency, perceptual fluency in particular, on item memory has been rarely explored from both behavioral and neural perspectives. To address these issues, an ERP experiment was conducted. Methods: Stimuli were encoded in the status of perceived vs. imagined, of either high or low frequency, manipulated by times of exposure (once or twice). Subsequent memory for the items was tested, during which ERP signals were recorded. Results and Conclusion: The findings of the old/new effects reveal the distinctiveness between perceived and imagined items, and demonstrate an influence of fluency, with higher accuracy for items of high fluency than those low fluent ones. The sensitivity of item memory to fluency was discussed in terms of the dual-process model, together with other possible accounts.