Neural correlates of information gain during search revealed by fMRI.

When confronted with uncertainty, humans engage in information-seeking behavior to gather sufficient information. Identifying the brain regions involved offers insight into the underlying cognitive mechanisms. Using Shannon information theory, we quantified the information contained in the image tiles presented in an fMRI experiment. Nineteen participants judged whether a caption described an image by viewing a sequence of tiles and signaling when it matched. Random-effects ANOVA and representational similarity analysis revealed that regions associated with information gain resulted in two complementary patterns. The first, involving right Ph2 and left hIP5, showed a graded relationship with information gain, consistent with tracking currently available perceptual evidence. The second, involving bilateral PGp with left hIP3 and left FG2, was more sensitive to intermediate information gain, possibly reflecting integrative processes relating accumulated visual information to task-relevant semantic expectations. These findings offer a neurocognitive framework for how information is acquired and evaluated during a sequential search.