Do people know when they are good at spotting liars? – Metacognitive efficiency in Lie Detection

We investigated whether the confidence in lie detection judgments is a signal for the accuracy of judgments. We argue that previous methods in tackling this question are inadequate as the assessment of judgment accuracy and confidence is confounded with response bias and lie detection performance. We addressed this confidence-accuracy puzzle by applying a hierarchical Bayesian approach based on Signal-Detection Theory to estimate metacognitive efficiency.Metacognitive efficiency describes individuals' insight into the accuracy of their judgments about truth and deception, but unlike previous measures, it is free of bias and independent of lie detection performance. In re-analyses of 12 studies (N=2817 participants in total), metacognitive efficiency was on average only about 23% of what would have been expected given participants’ discrimination performance. Hence, individuals largely lack metacognitive insight into the quality of their judgments, which is particularly problematic because they cannot reliably discriminate between lies and truths.