A recent study found that, across individuals, gray matter volume in the frontal polar region was correlated with visual metacognition capacity (i.e., how well one’s confidence ratings distinguish between correct and incorrect judgments). A question arises as to whether the putative metacognitive mechanisms in this region are also used in other metacognitive tasks involving, for example, memory. A novel psychophysical measure allowed us to assess metacognitive efficiency separately in a visual and a memory task, while taking variations in basic task performance capacity into account. We found that, across individuals, metacognitive efficiencies positively correlated between the two tasks. However, voxel-based morphometry analysis revealed distinct brain structures for the two kinds of metacognition. Replicating a previous finding, variation in visual metacognitive efficiency was correlated with volume of frontal polar regions. However, variation in memory metacognitive efficiency was correlated with volume of the precuneus. There was also a weak correlation between visual metacognitive efficiency and precuneus volume, which may account for the behavioral correlation between visual and memory metacognition (i.e., the precuneus may contain common mechanisms for both types of metacognition). However, we also found that gray matter volumes of the frontal polar and precuneus regions themselves correlated across individuals, and a formal model comparison analysis suggested that this structural covariation was sufficient to account for the behavioral correlation of metacognition in the two tasks. These results highlight the importance of the precuneus in higher-order memory processing and suggest that there may be functionally distinct metacognitive systems in the human brain.

A measurement scale should be short and quick to complete if it is to be practically useful. Drawing on data from a community-based survey of 2,178 people in Hong Kong, we compared five short forms (5- to 10-item) and the original version (20-item) of the Center for Epidemiologic Studies-Depression Scale (CES-D; Radloff, 1977) in predicting suicidal attempts and suicidal thoughts. Short forms with as few as nine items performed in ways very similar to the full version; a version with only five items had a detectable difference from the full version. Sensitivity, specificity, and predictive values in differentiating people with and without suicidal thought or attempt change almost linearly with the cut-offs.

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