Cognitive biases and nonverbal cue availability in detecting deception

In potentially deceptive situations, people rely on mental shortcuts to help process information. These heuristic judgments are often biased and result in inaccurate assessments of sender veracity. Four such biases - truth bias, visual bias, demeanor bias, and expectancy violation bias - were examined in a judgment experiment that varied nonverbal cue availability and deception. Observers saw a complete videotaped interview (full access to visual, vocal, and verbal cues), heard the complete interview (vocal and verbal access), or read a transcript (verbal access) of a truthful or deceptive suspect being questioned about a mock theft and then rated the interviewee on information, behavior, and image management and truthfulness. Results supported the presence of all four biases, which were most evident when interviewees were deceptive and observers had access to all visual, vocal, and verbal modalities. Deceivers' messages were judged as increasingly complete, honest, clear, and relevant; their behavior as more involved and dominant; and their overall demeanor as more credible, with the addition of nonverbal cues. Deceivers were actually judged as more credible than truthtellers in the audiovisual modality, whereas best discrimination and detection accuracy occurred in the audio condition. Results have implications for what factors influence judgments of a sender's credibility and accuracy in distinguishing truth from deception, especially under conditions where senders are producing messages interactively.