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Abstract:
Studies of human memory indicate that recognition judgments
can be made on the basis of assessments of item familiarity or on
the basis of recollection of associative information. Neuroimaging
studies have reported activity in the inferior frontal gryus (IFG)
and parahippocampal gyrus at encoding is greater for subsequently
recognized items than for subsequently forgotten items, but these
items typically differ in both the amount of familiarity and
recollection they elicit. In the present study, we used a
parametric approach to distinguish areas whose activity at encoding
predicted familiarity-based recognition from areas whose activity
predicted later recollection. During scanning, participants made
animacy or size judgments on concrete words, depending on the color
of the word. After scanning, they were given a recognition test and
asked to make confidence (1-6 scale) and associative memory
(animacy vs. size) judgments for each word. Recognition accuracy
varied continuously across response confidence, but accurate
associative memory judgments were observed only for the highest
confidence recognition responses. Preliminary event-related fMRI
analyses revealed a linear relationship between encoding activity
in the left IFG and subsequent recognition confidence. Thus,
encoding activity in the left IFG may predict familiarity-based
recognition, rather than subsequent recollection.
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