Neurale Mechanismen "intuitiver" Urteilsprozesse

Many of our decisions depend on intuitive judgments that can be
described as the capacity to implicitly evaluate the coherence of
context-relevant information without being able to provide an
explicit explanation. To study the neural mechanisms of implicit
and explicit perception of coherence, we performed an event-related
fMRI study using a semantic judgment task. Participants first had
to judge whether three simultaneously presented words were coherent
in the sense that they were all weakly related to a common
associate or incoherent if they were not. Subsequently,
participants had to provide, whenever possible, a solution word
that was semantically related to the word triad, thereby allowing
the following conditions: explicit perception of coherence (yes +
solution), implicit perception of coherence (yes + no solution),
and perception of incoherence (no + no solution). As a control
condition, pseudoword triads were presented. fMRI data analysis was
performed in SPM99 employing a random-effects model. Evaluation and
perception of semantic coherence was predominantly associated with
neural activity in left inferior and anteromedial prefrontal
regions, in the temporal cortex, precuneus, and right cerebellum.
Although no explicit solution was found, these regions were already
active in the implicit condition, indicating that the implicit
perception of semantic coherence is primarily based on the same
structures as the explicit perception, but does obviously not
suffice to retrieve an explicit answer. Implicit judgments of
coherence, as opposed to explicit judgments, were correlated with
an additional activation of bilateral parietal regions, the right
superior temporal sulcus, and the left posterior parahippocampal
gyrus. The common activation of the parietal association cortex and
right superior temporal sulcus in the implicit condition supports
the notion that intuitive judgments are based on an associative
evaluation of information coherence.