An ERP investigation into the strategic regulation of the fluency heuristic during recognition memory.

The goal of the present study was to determine whether masked repetition priming affects ERPs differently depending on whether or not participants are biased by task conditions to interpret enhanced perceptual fluency as evidence of prior study. Participants studied a list of words either in the visual modality or in the auditory modality and then performed a visual recognition memory test while ERPs were recorded. During the test, half the stimuli were preceded by a briefly presented matching prime word and half were preceded by a briefly presented non-matching prime word. Unlike in previous behavioral studies, masked repetition priming led to a reduction in positive recognition responses following auditory study, and had no effect following visual study, although post hoc analyses suggest that participants who received the visual study list may have relied on fluency to make some of their recognition decisions. Masked repetition priming also led to positive ERPs during two time windows-an early 300-500 ms window and a later 500-700 ms window. During the later time window, masked repetition priming exhibited a frontal scalp distribution that was most pronounced for participants who received the auditory study list. We suggest that this late frontal effect reflects participants' tendency to reject enhanced perceptual fluency as evidence of prior study.

Enhanced processing fluency leads to biases in source memory.

The present experiments were conducted to determine whether processing fluency affects source memory decisions. In the first three experiments, participants decided whether test items appeared in the same sensory modality (Experiments 1A, 1B) or perceptual form (font type, Experiment 2) at study and test. The results were consistent across the three studies and showed that perceptual priming leads to an increase in reports that stimuli were presented in the same sensory or perceptual form during the study and test phase. Experiment 3 showed that conceptual fluency affects source attributions in much the same way as perceptual fluency, and Experiment 4 showed that fluency is associated with a subjective experience of familiarity even when it might serve as a basis for source inference. These results are consistent with recent neuropsychological and neuroimaging evidence that familiarity-based processes contribute to source memory decisions under some circumstances, such as when items and contexts are unitized rather than merely bound together at encoding.

Source memory for unidentified stimuli.

Two experiments were conducted to determine whether participants have source memory for test stimuli that they cannot identify. Using a paradigm developed to investigate the phenomenon of recognition without identification (Peynircioglu, 1990), we found that even when participants could not identify a previously studied item, they nonetheless exhibited above-chance performance on a source discrimination task. Most surprising was that source accuracy for unidentified items was independent of old-new discrimination and not different from that of identified items. These results are interpreted as evidence that source memory is based on a continuous, as opposed to a threshold-like, process and suggest that recollection may, in some circumstances, contribute to the phenomenon of recognition without identification.