RT Journal Article
SR Electronic
T1 Expecting the Unexpected: Base-rate Neglect is Driven by Neural Activation of Common Cues
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 130716
DO 10.1101/130716
A1 Sean R. O’Bryan
A1 Darrell A. Worthy
A1 Evan Livesey
A1 Tyler Davis
YR 2017
UL http://biorxiv.org/content/early/2017/04/25/130716.abstract
AB The inverse base-rate effect (IBRE) describes an apparent irrationality in human decision making whereby people tend to ignore category base rates and choose rarer options when classifying ambiguous stimuli. According to some theories, people choose rare categories for ambiguous stimuli because rare cues draw more attention. Other theories predict that people choose rare categories because the ambiguous stimuli contrast with the more well-established patterns in common categories. In this experiment, we used multi-voxel pattern analysis to decode which features of ambiguous stimuli participants are activating during an fMRI version of the IBRE task. We show that individuals engage qualitatively distinct neural processes when making rare versus common responses: choosing a rarer category involved activation of cues associated with the common category. Consistent with inferential theories of base-rate neglect, our findings suggest that this surprising behavior involves a deliberative mechanism not explained by purely associative models.