Thursday, October 07, 2010

Brain correlates of introspective accuracy.

Knowing whether confidence predicts accuracy would be very useful, for example, in evaluating conflicting courtroom testimony in statements from witnesses who seem more or less confident. In a fascinating article, Fleming et al. find a relationship between the brain scans of people obtained by magnetic resonance imaging (MRI) and how seriously we should take their expressed level of confidence. They use a simple perceptual task, detecting the contrast between light and dark bars in a grating, which makes it possible to obtain both an objective measure of how accurate subjects are and a subjective measure of how confident they are in their judgments. They construct a measure of how accurate subjects are in their confidence judgments. The capacity for introspection, which can be regarded as one facet of metacognition (thinking about thinking), is shown to vary across individuals and to correlate positively with the gray matter volume of the frontopolar cortex (the frontmost region of the brain) and also with white matter in the tracts of the corpus callosum that connect these regions in the left and right hemispheres. From the abstract:
We show that introspective ability is correlated with gray matter volume in the anterior prefrontal cortex, a region that shows marked evolutionary development in humans. Moreover, interindividual variation in introspective ability is also correlated with white-matter microstructure connected with this area of the prefrontal cortex. Our findings point to a focal neuroanatomical substrate for introspective ability, a substrate distinct from that supporting primary perception.

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