Separable neural signatures of confidence during perceptual decisions.

Valentin Wyart,Pascal Mamassian,Tarryn Balsdon

doi:10.7554/elife.68491

Abstract

Perceptual confidence is an evaluation of the validity of perceptual decisions. While there is behavioural evidence that confidence evaluation differs from perceptual decision-making, disentangling these two processes remains a challenge at the neural level. Here, we examined the electrical brain activity of human participants in a protracted perceptual decision-making task where observers tend to commit to perceptual decisions early whilst continuing to monitor sensory evidence for evaluating confidence. Premature decision commitments were revealed by patterns of spectral power overlying motor cortex, followed by an attenuation of the neural representation of perceptual decision evidence. A distinct neural representation was associated with the computation of confidence, with sources localised in the superior parietal and orbitofrontal cortices. In agreement with a dissociation between perception and confidence, these neural resources were recruited even after observers committed to their perceptual decisions, and thus delineate an integral neural circuit for evaluating perceptual decision confidence.

Highlights

Whilst perception typically feels effortless and automatic, it requires probabilistic inference to resolve the uncertain causes of essentially ambiguous sensory input (Helmholtz, 1856)
We examined the neural signatures of perceptual decision commitment using a linear discriminant analysis of the spectral power of band-limited EEG oscillations
We examined the dynamic neural signals associated with suboptimal accumulation of evidence for evaluating confidence in perceptual decisions

Summary

Introduction

Whilst perception typically feels effortless and automatic, it requires probabilistic inference to resolve the uncertain causes of essentially ambiguous sensory input (Helmholtz, 1856). Human observers are capable of discriminating which perceptual decisions are more likely to be correct using subjective feelings of confidence (Pollack and Decker, 1958). These feelings of perceptual confidence have been associated with metacognitive processes (Fleming and Daw, 2017) that enable self-monitoring for learning (Veenman, Wilhelm, & Beishuizen, 2004) and communication (Bahrami et al, 2012; Frith, 2012). Perceptual confidence tends to reflect the quantity and quality of evidence used to make the perceptual decision (Vickers, 1979; Kepecs et al., 2008; Moreno-Bote, 2010) In this way, perceptual confidence is necessarily tethered to decision evidence: more evidence for the perceptual decision yields greater perceptual accuracy, and higher confidence. Confidence (or a nonhuman primate proxy for confidence) can be reliably predicted from the firing rates of neurons coding the perceptual decision itself (Kiani and Shadlen, 2009), suggesting that confidence may be a direct by-product of perceptual processing

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