A signal detection theoretic approach for estimating metacognitive sensitivity from confidence ratings

► Signal detection theory (SDT) predicts that task performance affects metacognition. ► Current measures of metacognition do not account for these confounds. ► Our new SDT method measures metacognitive performance without these confounds. ► Applying the method to data, we find observers are below SDT-optimal metacognition. ► We provide free Matlab code for performing the analysis.