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.

SummaryDetecting lies is crucial in numerous contexts, including situations in which individuals do not interact in their native language. Previous research suggests that individuals are perceived as less credible when they communicate in a nonnative compared with native language. The current study was the first to test this effect in truthful and fabricated messages written by native and nonnative English speakers. One hundred native English speakers judged the veracity of these messages, and overall, they proved less likely to believe and to correctly classify nonnative speakers' messages; differences in verbal cues between native and nonnative speakers' messages partly explained the differences in the judgments. Given the increased use of nonnative languages in a globalized world, the discrimination against nonnative speakers in veracity judgments is problematic. Further research should more thoroughly investigate the role of verbal cues in written and spoken nonnative language to enable the development of effective interventions.

Previous research has produced mixed results on the question of whether confidence in ad hoc veracity judgments can be used as an indicator of judgment accuracy. These studies have used a variety of measures to analyze the confidence‐accuracy relationship; however, they have rarely explicitly addressed why a particular measure was chosen and what its properties are. We theoretically and empirically examined previously used measures of metacognition in lie detection and report the results these measures yielded in re‐analyses of 12 lie detection studies (total N = 2817 participants). Regardless of the measure, none of the studies found a confidence‐accuracy relationship. Discrepancies between the measures are likely due to conceptual differences between them, emphasizing the importance of carefully selecting appropriate measures for the research question at hand. More work on the underlying processes of confidence judgments in lie detection is needed to improve the assessment of confidence and the selection of appropriate measures.

Research suggests that people differ more in their ability to lie than in their ability to detect lies. However, because studies have not treated senders and messages as separate entities, it is unclear whether some senders are generally more transparent than others or whether individual messages differ in their transparency of veracity regardless of senders. Variance attributable to judges, senders, and messages was estimated simultaneously using multiple messages from each sender (totaling more than 45,000 judgments). The claim that the accuracy of a veracity judgment depends on the sender was not supported. Messages differed in their detectability (21% explained variance), but senders did not. Message veracity accounted for most message variation (16.8% of the total variance), but other idiosyncratic message characteristics also contributed significantly. Consistent with the notion that a (mis)match between sender demeanor and veracity determines accuracy, lie and truth detectability differed individually within senders. Judges primarily determined variance in lie-versus-truth classifications (12%) and in confidence (46%) but played no role regarding judgment accuracy (< 0.01%). This work has substantial implications for the design and direction of future research and underscores the importance of separating senders and messages when developing theories and testing derived hypotheses.

Five experiments (total number of judging participants = 1309, four different kinds of stimulus materials with a total of 464 messages, total number of judgements  = 19,634) investigated the influence of personal uncertainty on the process of lie detection in social relationships. Building on and extending basic assumptions of uncertainty management models, we reasoned that uncertainty about themselves motivates people to evaluate the quality of their relationships. A crucial aspect of the quality of relationships with other people is the truthfulness with which they communicate verbally with you and anyone else. We proposed that if these assumptions are valid, reminding people of their personal uncertainties should lead them to use valid verbal cues in veracity judgements more. This enhanced usage of valid verbal cues should result in better accuracy in deception detection. An internal meta‐analysis of the five experiments reveals only a small, not significant, overall effect of uncertainty salience on detection accuracy with larger effect sizes for experiments conducted in the laboratory than for those conducted online. Hence, if personal uncertainty plays a role in the process of deception detection, it seems to be subject to moderators such as methodological or motivational factors.