Neural mechanisms of metacognitive improvements under speed pressure

The ability to accurately monitor the quality of one’s decisions (i.e., metacognition) is critical for adaptive decision-making. Past research has found that metacognition is enhanced when participants respond under speed pressure, possibly due to elaborated post-decisional evidence processing. Here, we investigated the time-course of evidence processing under different speed pressures using time-resolved analysis of electroencephalographic (EEG) data. Forty participants performed a motion discrimination task under short and long response deadlines. Following the initial response, participants reported how much they would like to change their mind, allowing us to assess their metacognitive ability. While participants responded faster and less accurately under speed pressure, their metacognitive sensitivity was higher than on long deadline trials. Moreover, metacognitive judgments were faster under speed pressure. To understand the neural mechanisms that regulate decision making, we analysed the centro-parietal positivity (CPP), a neural correlate of evidence accumulation. The CPP was significantly larger on trials with short deadlines, possibly reflecting the contribution of an evidence-independent urgency signal. For both short and long response deadlines, there was a dissociation between the pre-decisional and post-decisional CPP: greater pre-decisional CPP amplitude predicted less desire to change one’s mind, whereas greater post-decisional CPP amplitude predicted more desire to changes one’s mind. Collectively, our results suggest that superior metacognitive ability under speed pressure is not driven by differential evidence processing relative to long deadline trails, but may instead relate to greater overall CPP amplitude.