Conducting an investigation interview can be challenging. While both verbal and non-verbal cues are generally used to determine the truth, most investigators rely on non-verbal cues such as:

• too much or too little eye contact
• foot movement
• short responses
• shoulder shrugs
• pitch changes
• sweating
• changing the subject
• fidgeting
• lip licking
• face touching

Small talk baseline questioning is also used when conducting verbal interviews. Investigators and law enforcement usually use “small talk baseline” questioning to help them determine the truth. This involves asking nonthreatening questions and following up with additional questions that are directly designed to uncover the truth. They then compare all the answers and the behaviors to come to a conclusion.

While these are all good indicators to help determine if someone is lying, there are other ways to approach this. Finding the truth is often much more complicated.

Need a quick tool to help you to tell when an interview subject is lying? Download the Detecting Deception Cheat Sheet.

Verbal Cues to Detect Deception

One of the newer thoughts on determining if someone is lying actually depends mainly on verbal cues and less on non-verbal cues. I recently came across information on a newly published study, where the University of Bergamo (Italy)’s Letizia Caso and colleagues (2019) sought to determine whether liars can be exposed by comparing their lies to other statements that they make in conversation.

They do not believe the small talk baseline is reliable. The authors feel that the cues to detecting deception as tested in experimental methods by psychologists are “faint and unreliable,” and that “truth tellers and liars do not differ much” (pp. 1-2). They feel that interviewees can easily cover up a lie. The reverse is also true where an innocent person can be nervous and exhibit signs that may point to them being guilty or lying.

Related: 44 Investigation Interview Questions for the Complainant, Subject and Witnesses

Open-Ended Questions

The researchers feel that a “comparable truth baseline” in which the interviewer talks about similar topics within the same portion of the interview rather than switching from casual to interrogative questions may be more effective. As the authors point out in an earlier paper (Palena et al., 2018, p. 125), “Comparable means that the baseline the investigator uses must be similar in content, stakes, cognitive and emotional involvement to investigative questions.” Essentially, this means that your line of questioning must not vary from casual to specific or change in tone. Asking open-ended questions is an integral part of using the comparable truth baseline.

Download the Top 20 Questions to Ask in an Investigation Interview.

In the researcher’s experiment, they determined liars vs. truth-tellers by using the standard nonverbal cues and the outcome was that both liars and truth-tellers behaved identically using the small talk baseline. However, when using the comparable truth condition and asking more open-ended questions, liars were not as good at providing specific facts or information. The small-talk baseline method may give them time to adjust to the line of questioning, making it easier to lie.

When conducting an investigation interview you may want to try asking more open-ended questions as opposed to relying on traditional small-talk baseline questioning or the standard non-verbal cues.