Empirical evidence indicates that people can provide accurate evaluations of their own thoughts and actions by means of both error detection and confidence judgments. This study investigates the foundations of these metacognitive abilities, specifically focusing on the relationship between confidence and error judgments in human perceptual decision making. Electroencephalography studies have identified the error positivity (Pe)-an event-related component observed following incorrect choices-as a robust neural index of participants' awareness of their errors in simple decision tasks. Here we assessed whether the Pe also varies in a graded way with participants' subjective ratings of decision confidence, as expressed on a 6-point scale after each trial of a dot count perceptual decision task. We observed clear, graded modulation of the Pe by confidence, with monotonic reduction in Pe amplitude associated with increasing confidence in the preceding choice. This effect was independent of objective accuracy. Multivariate decoding analyses indicated that neural markers of error detection were predictive of varying levels of confidence in correct decisions, including subtle shifts in highconfidence trials. These results suggest that shared mechanisms underlie two forms of metacognitive evaluation that are often treated separately, with consequent implications for current theories of their neurocognitive basis.

There is currently little direct evidence regarding the function of subjective confidence in decision making: The tight correlation between objective accuracy and subjective confidence makes it difficult to distinguish each variable's unique contribution. Here, we created conditions in a perceptual decision task that were matched in accuracy but differed in subjective evaluation of accuracy by orthogonally varying the strength versus variability of evidence. Confidence was reduced with variable (vs. weak) evidence, even across conditions matched for difficulty. Building on this dissociation, we constructed a paradigm in which participants ( N = 20) could choose to seek further information before making their decision. The data provided clear support for the hypothesis that subjective confidence predicts information seeking in decision making: Participants were more likely to sample additional information before giving a response in the condition with low confidence, despite matched accuracy. In a preregistered replication ( N = 50), these findings were replicated with increased task difficulty levels.

HighlightsWe propose a ‘dual systems’ framework for thinking about metacognition.System 1 metacognition is for ‘intra-personal’ cognitive control.System 2 metacognition is for ‘supra-personal’ cognitive control.The latter allows agents to share metacognitive representations.This sharing creates benefits for the group and facilitates cumulative culture.