Confidence is predicted by pre- and post-choice decision signal dynamics

It is well established that one’s confidence in a choice can be influenced by new evidence encountered after commitment has been reached, but the processes through which post-choice evidence is sampled remain unclear. To investigate this, we traced the pre- and post-choice dynamics of electrophysiological signatures of evidence accumulation (Centro-parietal Positivity, CPP) and motor preparation (mu/beta band) to determine their sensitivity to participants’ confidence in their perceptual discriminations. Pre-choice CPP amplitudes scaled with confidence both when confidence was reported simultaneously with choice, or when reported 1-second after the initial direction decision. When additional evidence was presented during the post-choice delay period, the CPP continued to evolve after the initial choice, with a more prolonged build-up on trials with lower confidence in the alternative that was finally endorsed, irrespective of whether this entailed a change-of-mind. Further investigation established that this pattern was accompanied by earlier post-choice CPP peak latency, earlier lateralisation of motor preparation signals toward the ultimately chosen response, and faster confidence reports when participants indicated high certainty that they had made a correct or incorrect initial choice. These observations are consistent with confidence-dependent stopping theories according to which post-choice evidence accumulation ceases when a criterion level of confidence in a choice alternative has been reached. Our findings have implications for current models of choice confidence, and predictions they may make about EEG signatures.