Decision-making does not culminate when a choice is made. Instead, humans continue to evaluate their decisions through post-decisional reflection, and when needed, use new evidence to update the original decision. Post-decisional evaluation enables the formation of confidence in a decision, and detection and of revision errors. These processes belong to a class cognitive processes labelled metacognition—the capacity to monitor, evaluate, and regulate one’s own cognitive processing. Understanding post-decisional dynamics is especially consequential in clinical decision making, where initial decisions are often made under uncertainty and time pressure, and may need to be revised as new information emerges.

In this review, we synthesise theoretical, behavioural, and neuroscientific work on metacognition and post-decisional processing, focusing on evidence accumulation frameworks. We describe how classic decision models, such as drift–diffusion models, can be extended beyond the point of choice to account for confidence, error detection, and changes of mind. We discuss how confidence is dynamically updated by post-decisional information, underpinned by neural signatures of continued evidence accumulation and performance monitoring. We also examine how these processes are shaped by systematic biases, including a confidence-dependent confirmation bias.

Finally, we highlight recent computational approaches that reveal different sources of metacognitive bias, including distortions in post-decisional accumulation and differences in how evidence is interpreted, offering new explanations of individual differences in belief updating. In clinical decision-making, such mechanisms may determine whether practitioners appropriately revise or persist with initial judgments, with important implications for diagnostic accuracy and patient outcomes.