Competing Neural Decision Variables in Human Frontal Cortex Shape Decision Confidence

Mounting evidence indicates that decisions emerge from a competition between populations of neurons encoding the different choice options. Theoretical models propose that the outcome of this competition may shape agents confidence in their decisions. But measuring the underlying neural dynamics of this competition has so far been challenging. Here, we developed a magnetoencephalography source imaging approach to simultaneously track competing neural decision variables in human frontal cortex during decision formation. This revealed negative intrinsic correlations between decision variables, a signature of intracortical, inhibitory interactions. Both "winning" and "losing" decision variables uniquely contribute to confidence, with a stronger impact of the winner. These asymmetric contributions constrain a dynamical model of decision and confidence formation, which accurately captures several other diagnostic behavioral and neural signatures, including the anti-correlation between decision variables. Our approach opens a new window on the distributed neural mechanisms underlying decision-making and confidence formation.