A liar and a copycat: nonverbal coordination increases with lie difficulty.

Area of Science:

• Psychology
• Nonverbal Communication
• Deception Detection

Background:

• Existing research on deception often overlooks the dynamic interplay between deceivers and interviewers.
• Studies typically analyze liars' behaviors in isolation, neglecting the concept of joint action.

Purpose of the Study:

• To investigate the relationship between lie difficulty and nonverbal coordination between interviewers and interviewees.
• To explore how attentional focus and interviewer suspicion influence this coordination during deception.

Main Methods:

• Two experiments were conducted, measuring nonverbal coordination using motion-capture data and dynamic time warping.
• Experiment 1 varied lie difficulty (truth, easy, difficult, very difficult).
• Experiment 2 introduced instructions affecting interviewees' attention to verbal or nonverbal cues from the interviewer.

Main Results:

• Nonverbal coordination between interviewers and interviewees significantly increased as the difficulty of the lie increased.
• This coordination enhancement was independent of the interviewee's attentional focus (verbal vs. nonverbal).
• Interviewer's suspicion level did not affect the observed increase in nonverbal coordination with lie difficulty.

Conclusions:

• Increased nonverbal coordination with lie difficulty suggests a reliance on automated processes, such as mimicry.
• Cognitive load associated with more complex deception may trigger these automatic synchronization mechanisms.
• The findings challenge the focus on individual behaviors in deception research, highlighting the importance of dyadic interactions.