Confidence in masked orientation discrimination decisions is informed by both evidence and visibility

Kurzfassung/Abstract

How do human observers determine their degree of belief of being correct in a 22 decision about a visual stimulus, i.e. their confidence? According to prominent theories of 23 confidence, the quality of stimulation should be positively related to confidence in correct 24 decisions and negatively to confidence in incorrect decisions. However, in a backwards-25 masked orientation task with varying stimulus-onset asynchrony (SOA), we observed that 26 confidence in incorrect decisions increased with stimulus quality as well. Model fitting to 27 decision and confidence data revealed that the best explanation for the present data was the 28 new weighted evidence and visibility model, according to which confidence is determined by 29 evidence about the orientation as well as the general visibility of the stimulus. Signal 30 detection models, post-decisional accumulation models, two-channel models, and decision-31 time based models were all unable to explain the pattern of confidence as a function of SOA 32 and decision correctness. We suggest that the metacognitive system combines several cues to 33 being correct in the decision about the visual stimulus to calculate decision confidence.