Person:

Sperling, Reisa

Metamemory refers to knowledge and monitoring of one's own memory. Metamemory monitoring can be done prospectively with respect to subsequent memory retrieval or retrospectively with respect to previous memory retrieval. In this study, we used fMRI to compare neural activity during prospective feeling-of-knowing and retrospective confidence tasks in order to examine common and distinct mechanisms supporting multiple forms of metamemory monitoring. Both metamemory tasks, compared to non-metamemory tasks, were associated with greater activity in medial prefrontal, medial parietal, and lateral parietal regions, which have previously been implicated in internally directed cognition. Furthermore, compared to non-metamemory tasks, metamemory tasks were associated with less activity in occipital regions, and in lateral inferior frontal and dorsal medial prefrontal regions, which have previously shown involvement in visual processing and stimulus-oriented attention, respectively. Thus, neural activity related to metamemory is characterized by both a shift toward internally directed cognition and away from externally directed cognition. Several regions demonstrated differences in neural activity between feeling-of-knowing and confidence tasks, including fusiform, medial temporal lobe, and medial parietal regions; furthermore, these regions also showed interaction effects between task and the subjective metamemory rating, suggesting that they are sensitive to the information monitored in each particular task. These findings demonstrate both common and distinct neural mechanisms supporting metamemory processes and also serve to elucidate the functional roles of previously characterized brain networks.

Successful memory typically implies both objective accuracy and subjective confidence, but there are instances when confidence and accuracy diverge. This dissociation suggests that there may be distinct neural patterns of activation related to confidence and accuracy. We used event-related functional magnetic resonance imaging to study the encoding of novel face–name associations, assessed with a postscan memory test that included objective measures of accuracy and subjective measures of confidence. We showed specific neural activity in the left inferior prefrontal cortex associated with trials when subjects expressed high confidence that they had chosen the correct name for the face and made a correct identification. Moreover, we found that this region was also associated with imparting high confidence when subjects chose the incorrect name. However, medial temporal lobe regions showed activity only for high-confidence correct trials. Many functional magnetic resonance imaging studies have shown that the medial temporal lobe and left prefrontal regions are particularly important for the successful formation of memories by using a combination of subjective and objective measures. Our findings suggest that these regions may be differentially involved in the objective and subjective components of memory and that the origins of confidence–accuracy dissociations may be related to incomplete activation of the neural pattern seen in successful encoding. These findings may also aid understanding of eyewitness misidentifications and memory distortions.

Although several studies have examined the neural basis for age-related changes in objective memory performance, less is known about how the process of memory monitoring changes with aging. The authors used functional magnetic resonance imaging to examine retrospective confidence in memory performance in aging. During low confidence, both younger and older adults showed behavioral evidence that they were guessing during recognition and that they were aware they were guessing when making confidence judgments. Similarly, both younger and older adults showed increased neural activity during low- compared to high-confidence responses in the lateral prefrontal cortex, anterior cingulate cortex, and left intraparietal sulcus. In contrast, older adults showed more high-confidence errors than younger adults. Younger adults showed greater activity for high compared to low confidence in medial temporal lobe structures, but older adults did not show this pattern. Taken together, these findings may suggest that impairments in the confidence-accuracy relationship for memory in older adults, which are often driven by high-confidence errors, may be primarily related to altered neural signals associated with greater activity for high-confidence responses.