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The present neuroimaging study examines how repetition-related neural attenuation effects differ as a function of the perceptual similarity of the repetition and subsequent memory. One previous study (Turk-Browne et al., 2006) reported greater attenuation effects for subsequent hits than for misses. Another study (Wagner et al., 2000) found that neural attenuation is negatively correlated with subsequent memory. These opposing results suggest that repetition-related neural attenuation for subsequent hits and misses may be driven by different factors. In order to investigate the factors that affect the degree of neural attenuation, we varied perceptual similarity between repetitions in a scanned encoding phase that was followed by a subsequent memory test outside the scanner. We demonstrated that the degree of neural attenuation in the object processing regions depends on the interaction between perceptual similarity across repeated presentations and the quality their encodings. Specifically, the same areas that decreased neural signal for repetitions of same exemplars that were subsequently recognized with confidence that the repetitions were identical showed a decrease in neural signal for different-exemplar misses but not for the corresponding subsequently recognized hits. Our results imply that repetition-related neural attenuation should be related to the more efficient processing of perceptual properties of the stimuli only if subjects are able to subsequently remember the stimuli. Otherwise, the cause of attenuation may be in the failure to encode the stimuli on the second presentation as shown by the pattern of neural attenuation for the different-exemplar misses., (Copyright © 2010 Elsevier Inc. All rights reserved.)

In Koriat's paper "The Feeling of Knowing: Some Metatheoretical Implications for Consciousness and Control," he asserts that the feeling of knowing straddles the implicit and explicit, and that these conscious feelings enter into a conscious control process that is necessary for controlled behavior. This assertion allows him to make many speculations on the nature of consciousness itself. We agree that feelings of knowing are produced through a monitoring of one's knowledge, and that this monitoring can affect the control of behavior such as whether or not to search memory for an answer. Further, we believe that monitoring of performance with a strategy can also affect cognition control and strategy selection; however, we also believe that frequently this monitoring and control occurs without conscious awareness. Feeling of knowing has received an inordinate amount of attention because it lies behind the highly recognizable tip-of-the-tongue phenomenon that represents one of the rare cases of conscious monitoring. There are other feelings of knowing which are much more common and are not accompanied by conscious awareness. These are evident in the early selection of a strategy for answering a problem. In our view, the research on feeling of knowing will not resolve the question of whether consciousness is merely epiphenomenal., (Copyright 2000 Academic Press.)