Parsing communication duration and diagnostic question effects in deception detection

An experiment (N = 155) testing mere duration and diagnostic content hypotheses in deception detection is reported. To the extent that observable behavioral cues aid deception detection, longer behavioral samples may provide a greater opportunity for cues to emerge, thereby increasing accuracy relative to the observation of short snippets of interviews. In contrast, truth-default theory proposes that question-and-answer content is a moderator, and more is only better when questions prompt diagnostic communication content. A 2 × 2 experiment varied communication duration (short, long) and questioning approach (more, less diagnostic). Consistent with the diagnostic content hypothesis, the results suggest that duration only mattered within the more diagnostic question condition. In the less diagnostic question condition, the results mirrored prior meta-analysis regardless of duration. The findings align with truth-default theory and provide evidence for a theory-based approach to improving deception detection.