Observers can discriminate between correct versus incorrect perceptual decisions with feelings of confidence. The centro-parietal positivity build-up rate (CPP slope) has been suggested as a likely neural signature of accumulated evidence, which may guide both perceptual performance and confidence. However, CPP slope also covaries with reaction time, which also covaries with confidence in previous studies, and performance and confidence typically covary; thus, CPP slope may index signatures of perceptual performance rather than confidence per se. Moreover, perceptual metacognition – including neural correlates – has largely been studied in vision, with few exceptions. Thus, we lack understanding of domain-general neural signatures of perceptual metacognition outside vision. Here we designed a novel auditory pitch identification task and collected behavior with simultaneous 32-channel EEG in healthy adults. Participants saw two tone labels which varied in tonal distance on each trial (e.g., C vs D, C vs F), then heard a single auditory tone; they identified which label was correct and rated confidence. We found that pitch identification confidence varied with tonal distance, but performance, metacognitive sensitivity (trial-by-trial covariation of confidence with accuracy), and reaction time did not. Interestingly, however, while CPP slope covaried with performance and reaction time, it did not significantly covary with confidence. We interpret these results to mean that CPP slope is likely a signature of first-order perceptual processing and not confidence-specific signals or computations in auditory tasks. Our novel pitch identification task offers a valuable method to examine the neural correlates of auditory and domain-general perceptual confidence.

32-channel EEG data (Ag/AgCl) were recorded using a BrainVision ActiCap system (Brain Products GmbH, Munich, Germany) via the BrainVision Recorder software (Version 1.21.0303, Brain Products GmbH, Munich, Germany) at 500 Hz sampling frequency. All electrodes were mounted in an elastic cap according to the international 10/20 system (Oostenveld & Praamstra, 2001), and were grounded with a forehead ground and online referenced to Cz. Impedances were kept below 20 kΩ on average, and an antialiasing low-pass fi2lter of 245 Hz was applied via an ActiCHamp amplifier (Brain Products GmbH, Munich, Germany). Conductive gel was applied to maintain the contact between the electrodes and the scalp. Event and response triggers were synchronized with the recorded EEG signal via TTL signals sent through the VPixx DATAPixx system.