We asked young adults to categorize written object descriptions into one of two categories,
based on a rule or on overall similarity, while we monitored regional brain activity with
functional magnetic resonance imaging (fMRI). We found significantly greater recruitment of
left dorsolateral prefrontal cortex for rule-based categorization in direct comparison with
similarity-based categorization. Recruitment of right ventral frontal cortex and thalamus was
uniquely associated with rule-based categorization as well. These observations lend …