Insula and striatum mediate the default bias.
Humans are creatures of routine and habit. When faced with situations in which a default option is available, people show a consistent tendency to stick with the default. Why this occurs is unclear. To elucidate its neural basis, we used a novel gambling task in conjunction with functional magnetic resonance imaging. Behavioral results revealed that participants were more likely to choose the default card and felt enhanced emotional responses to outcomes after making the decision to switch. We show that increased tendency to switch away from the default during the decision phase was associated with decreased activity in the anterior insula; activation in this same area in reaction to "switching away from the default and losing" was positively related with experienced frustration. In contrast, decisions to choose the default engaged the ventral striatum, the same reward area as seen in winning. Our findings highlight aversive processes in the insula as underlying the default bias and suggest that choosing the default may be rewarding in itself.
Medical Research Council Cognition and Brain Sciences Unit, Cambridge CB2 7EF, UK. ry223@cam.ac.uk
Rongjun
R
Yu
Dean
D
Mobbs
Ben
B
Seymour
Andrew J
AJ
Calder
D000328:Adult; D001479:Basal Ganglia / Q000033:anatomy & histology / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D003657:Decision Making / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009042:Motivation / Q000502:physiology; D009483:Neuropsychological Tests / Q000592:standards; D015588:Observer Variation; D011597:Psychomotor Performance / Q000502:physiology; D012201:Reward; D013647:Task Performance and Analysis; D055815:Young Adult