Cognitive training increases sensitivity to internal uncertainty during decision-making

Metacognitive awareness of decision quality is important for adaptive decision-making. One marker of decision quality is the strength of internal evidence accumulation. Increasing sensitivity to evidence accumulation thus offers a potential mechanism for improving metacognition. To test this hypothesis, we trained two groups of participants (n = 34 per group) to reproduce the motion direction of one of two sequentially presented dot-motion stimuli. Participants in the forced-choice group were instructed which stimulus to respond to, whereas those in the free-choice group chose which stimulus they responded to. This manipulation targeted the instrumental value of metacognitive awareness, as participants in the free-choice group could use metacognition to optimize their choices. Before and after training, participants completed a near-transfer motion-discrimination task and provided metacognitive judgments, allowing us to assess how training altered sensitivity to evidence accumulation. Evidence accumulation was measured using the centroparietal positivity (CPP) and the drift rate. Participants in both groups performed better and exhibited improved metacognition following training. Training increased sensitivity to the predecisional CPP in the free-choice group and to the postdecisional CPP in the forced-choice group. Moreover, training increased sensitivity to the drift rate in the free-choice group but not the forced-choice group. These results provide novel insights into the neurocognitive mechanisms underlying training-induced improvements in metacognition.NEW & NOTEWORTHY We tested whether a novel training paradigm could increase participants' sensitivity to internal signals of decision quality and improve their decision-making and metacognition. Participants' behavioral performance improved following training, and this was accompanied by increased strength of the relationship between the centro-parietal positivity, a neural correlate of evidence accumulation, and participants' metacognitive judgments. Our work demonstrates that training can increase sensitivity to internal signals of decision uncertainty.