Does (Biasing) Nonverbal Information Deteriorate the Accuracy of the Take-the-Best Heuristic for Deception Detection?

People are poor lie detectors, partly because they hold false beliefs about nonverbal cues to deception. Here, we investigated if guiding people to rely only on a message's detailedness (“take-the-best”) boosts their lie detection and to what extent such heuristic judgments are immune to nonverbal information. In three studies (Ns = 109, 88 and 144), participants made detailedness-based veracity judgements, of text versus video statements (Study 1), or of statements without or with biasing nonverbal behavior (truth tellers diverting, liars maintaining gaze; Studies 2 and 3). Compared to unguided judgements, participants using the heuristic method achieved higher deception detection accuracy throughout. Mere access to nonverbal behavior did not deteriorate performance (Study 1), but the heuristic was not fully immune to biasing nonverbal behavior (Studies 2, 3). Our findings challenge the lay notion that access to nonverbal behavior benefits deception detection and suggest that only focusing on diagnostic cues improves lie detection.