Neural mechanisms of confidence propagation in hierarchical partially observable decision-making.

Our daily decision-making often occurs in environments that are partially observable and hierarchically organized, introducing multiple sources of uncertainty in the decision-making process. To investigate how the brain incorporates subjective confidence stemming from the hierarchical partially observable structure, we developed the twenty-one task, a "blind" blackjack card game with hidden card-deck types. Combining computational modeling and neuroimaging demonstrates that the ventral insular cortex (vIC), presupplementary motor area (SMA), and dorsal anterior cingulate cortex (dACC) encode confidence in deck-type inference during decision-making. Furthermore, individuals vary in how they modulate value-belief and decision confidence based on their deck confidence; these modulations are predicted by the effect of deck confidence on functional connectivity between the vIC and pregenual cingulate cortex, and between the preSMA/dACC and dorsomedial prefrontal cortex, respectively. Our findings suggest that in hierarchical partially observable environments, confidence for higher-order belief affects lower-order confidence through multiple pathways.