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Abstract:
There are two main stages in learning a rule to determine
concept membership: (1) forming and testing plausible rules, and
(2) applying the determined rule to new instances. Participants had
fMRI images recorded while performing a task (Levine, 1975) in
which rule formation and rule application can be separated. On each
trial, two stimuli appeared that differed on several features
(e.g., color, shape); participants selected one of the stimuli,
then received feedback. Participants were told to form and test
unidimensional rules (e.g., always choose the blue stimulus), and
once they had determined the correct rule to continue applying it
until 12 trials have passed. The trial of last error was used to
separate trials during which rules were formed and tested from
trials during which the correct rule was applied. Participants also
performed a baseline task in which they were told to select which
stimulus had a particular feature. FMRI activation was compared for
the three conditions (rule formation, application, and baseline)
using SPM99. Rule formation and application both activated (in
comparison to baseline) the bilateral inferior frontal lobe (BA 47,
45), the bilateral striatum, and areas of the medial frontal lobe
including the anterior cingulate. Rule formation led to higher
activity than rule application in bilateral dorsolateral prefrontal
cortex (BA 9, 44, 6) and bilateral parietal lobe (BA 39, 40,
7).
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