Article Categories


Voice Quality Changes – Truth or Deception
(A Deception Research Update)

by Stan B. Walters, CSP
“The Lie Guy®”

Among the multiple channels of communication that a person can use, the “voice channel” possesses three sub-channels: verbal content, thought line and voice quality. Voice quality is defined as the rate of speech, voice pitch and volume. The question for the interviewer is “Are any changes in voice quality characteristics broadcast by the subject reliable cues of deception?”

To answer this question, research studies have been testing the significance of voice changes exhibited by subjects in “live” interviews and interrogations. In the past, deception studies have used “staged” or “controlled” settings that allow for consistent interview conditions but don’t reflect real life reactions seen by interviewers. An extensive research study has been conducted using live interrogations in which a subject’s specific statements have been confirmed as truthful or deceptive. Voice quality changes where among the behavioral changes analyzed by the observers for their ability to isolate truthful from deceptive statements.

Results from this study have determined that when a subject is not experiencing elevated levels of stress and was at the same time being truthful, the subject did not show any significant voice quality changes. Obviously there is not much of a surprise in the results of this part of the study but we do have a critical baseline measurement. When the subject was under stress the voice quality cues did in fact show significant increase in the pitch of the voice, volume and the words per minute or at least in some of variation or combination of the characteristics. Interestingly, the subject was not being deceptive at the same time the voice quality changes occurred.

When false or deceptive statements where analyzed for the presence of voice quality changes, some interesting results were revealed. It was learned that as expected, subjects under significant stress and being deceptive did show changes in voice quality. However, it was also learned that deceptive subjects who are under stress might not show any significant changes in voice quality.

The conclusion about voice quality changes is that such changes can occur when subjects are being both truthful and deceptive and are therefore not reliable signs of deception. In addition, voice quality changes can be associated with an increase in stress in a subject but the lack of voice quality changes do not mean that your subject is not experiencing elevated levels of stress. He or she may in fact be able to exhibit their stress through other verbal or nonverbal channels.

Avoiding Critical Issue Overload

by Stan B. Walters, CSP
“The Lie Guy®”

You finally have your subject in the interview room. You’ve built a substantial case against your subject and you’re sure there’s no way he or she can deny the overwhelming information you compiled against them. When the time is right you “unload” on the subject. You give them “both barrels” and then you stand back waiting for your subject to crumble under the sheer wait of the proof of your case. After a short pause your subject simply tells you you’re wrong and says “No.” So what happened? You had a great interrogation dialogue all set up. Simple. It was a case of “critical issue overload.” You pushed too much information on your subject all at once and forced your subject to reject the entire argument of proof thereby disabling your interview.

First, your subject was heavily under stress to begin with. Now you have forced your subject into making a single critical decision with what appears to them to be of totally overwhelming proportions. To him or her it is the most expedient way to escape from the pressure that the reality they’ve just been forced to confront.

Second, you set yourself up to have your interview argument to be shut down with a single simple answer – No. Your subject saw that you gave them a simple “out” and they took it leaving your argument hanging and unresolved.

Avoid “critical issue overload” techniques in the interview room. Spread out your case information by addressing smaller more manageable arguments. This keeps your subject from feeling mentally and emotionally overwhelmed with the reality of the facts they may be facing. String out your case arguments addressing only one issue at a time. Now your subject is forced to deal with each issue one at a time creating a training effect. Even though they have just dealt with one issue, there’s the next coming right behind the first. You are also more likely to get a toehold on your subject’s resistance by getting acceptance on a few issues. Once you win one or two points, it much easier to argue subsequent proof and avoid one mass rejection of your entire case.