Do performance-monitoring related cortical potentials mediate fluency and difficulty effects on decision confidence?

It remains unclear to what extent the performance-monitoring (PM) processes involved in perceptual decisions are also involved in more complex reasoning decisions. To address this problem, we examined whether PM-related cortical potentials known to correlate with confidence ratings in the context of simple perceptual decisions also correlate with confidence ratings in a more complex reasoning task. In an EEG experiment, 49 participants had to quickly decide whether an equation (e.g. 9 * 7 = 65) was correct or incorrect and then report their confidence in that decision. Task difficulty and response fluency were varied to manipulate confidence. Pooling responses across correct as well as incorrect trials, we analyzed amplitudes of Error-Related Negativity (pooled ERN) and Error Positivity (pooled Pe). We found that pooled ERN but not pooled Pe had a positive significant correlation with decision confidence and that unpooled ERN correlated with confidence for correct, but not for error trials. Further analysis indicated that although pooled ERN correlated with task difficulty, neither pooled or unpooled potentials mediated the effects of difficulty or fluency on confidence. These results suggest that pooled ERN might reflect implicit performance monitoring and that confidence for simple perceptual and complex reasoning decisions may rely on different neural mechanisms.

Perceptual decision confidence is sensitive to forgone physical effort expenditure

Contemporary theoretical accounts of metacognition propose that action-related information is used in the computation of perceptual decision confidence. We investigated whether the amount of expended physical effort, or the 'motoric sunk cost' of a decision, influences perceptual decision confidence judgements in humans. In particular, we examined whether people feel more confident in decisions which required more effort to report. Forty-two participants performed a luminance discrimination task that involved identifying which of two flickering grayscale squares was brightest. Participants reported their choice by squeezing hand-held dynamometers. Across trials, the effort required to report a decision was varied across three levels (low, medium, high). Critically, participants were only aware of the required effort level on each trial once they had initiated their motor response, meaning that the varying effort requirements could not influence their initial decisions. Following each decision, participants rated their confidence in their choice. We found that participants were more confident in decisions that required greater effort to report. This suggests that humans are sensitive to motoric sunk costs and supports contemporary models of metacognition in which actions inform the computation of decision confidence.

Metacognition-related regions modulate the reactivity effect of confidence ratings on perceptual decision-making

Prompting confidence ratings following perceptual decision-making could significantly affect the decision-making per se, a phenomenon known as the reactivity effect. The current study aimed to explore the neural substrates underlying the reactivity effect by comparing behavioral and functional magnetic imaging data between when participants making decisions with prompted confidence ratings (DCR+) and when without providing confidence ratings (DCR-). The results showed that DCR+ was associated with longer decision response times (RTs) and higher accuracy than DCR-. The analysis of fMRI data revealed significantly increased activation in the DCR+ condition, relative to the DCR- condition, in multiple metacognition-related regions including the left supplementary motor area, left dorsal anterior cingulate cortex, left opercular part of the inferior frontal gyrus, and bilateral precuneus. Changed beta values (Beta_DCR+ minus Beta_DCR-) of these clusters were correlated with the changed decision RTs between the two conditions (ΔRT = RT_DCR+ - RT_DCR-). Psychophysiological interaction analysis revealed increased functional connectivity between the left supplementary motor area and the right inferior parietal lobe in the DCR+ condition than the DCR- condition. Further multiple regression analysis found that ΔRTs was significantly associated with activities in the bilateral dorsal anterior cingulate cortex and supplementary motor area. Together, this study found that provide confidence ratings significantly changed online decision-making while activating multiple metacognition-related regions. The activity of metacognition-related regions may be a crucial part of the neural mechanisms underlying the reactivity effect of confidence ratings on perceptual decision-making.

Dopaminergic and Prefrontal Basis of Learning from Sensory Confidence and Reward Value

Deciding between stimuli requires combining their learned value with one's sensory confidence. We trained mice in a visual task that probes this combination. Mouse choices reflected not only present confidence and past rewards but also past confidence. Their behavior conformed to a model that combines signal detection with reinforcement learning. In the model, the predicted value of the chosen option is the product of sensory confidence and learned value. We found precise correlates of this variable in the pre-outcome activity of midbrain dopamine neurons and of medial prefrontal cortical neurons. However, only the latter played a causal role: inactivating medial prefrontal cortex before outcome strengthened learning from the outcome. Dopamine neurons played a causal role only after outcome, when they encoded reward prediction errors graded by confidence, influencing subsequent choices. These results reveal neural signals that combine reward value with sensory confidence and guide subsequent learning.