RT Journal Article
SR Electronic
T1 Model-based fMRI Reveals Dissimilarity Processes Underlying Base Rate Neglect
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 130716
DO 10.1101/130716
A1 Sean R. O’Bryan
A1 Darrell A. Worthy
A1 Evan J. Livesey
A1 Tyler Davis
YR 2018
UL http://biorxiv.org/content/early/2018/03/26/130716.abstract
AB Extensive evidence suggests that people use base rate information inconsistently in decision making. A classic example is the inverse base rate effect (IBRE), whereby participants classify ambiguous stimuli sharing features of both common and rare categories as members of the rare category. Computational models of the IBRE have either posited that it arises from associative similarity-based mechanisms or dissimilarity-based processes that may depend upon higher-level inference. Here we develop a hybrid model, which posits that similarity- and dissimilarity-based evidence both contribute to the IBRE, and test it using functional magnetic resonance imaging data collected from human subjects completing an IBRE task. Consistent with our model, multivoxel pattern analysis reveals that activation patterns on ambiguous test trials contain information consistent with dissimilarity-based processing. Further, trial-by-trial activation in left rostrolateral prefrontal cortex tracks model-based predictions for dissimilarity-based processing, consistent with theories positing a role for higher-level symbolic processing in the IBRE.