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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.

Which Interview Technique Works Best?

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

One question I’m frequently asked is which interview and interrogation technique works the best. The best answer I can give is whichever technique you used when the subject confessed. Although that answer may sound vague the reality is that the response is very accurate. There is no uniform method or technique that will be successful in every interview situation. As we discussed in the June issue, the successful interviewer is the one who learns how to adapt to the unique personality and behavior characteristics of the subject that happen to be interviewing.

To be a little more specific, we can refer to several scientific studies that have observed, documented and analyzed several hundred investigative interviews. The findings of these observational studies are quite interesting in that they report that there are interview and interrogation tactics that appear to regularly be most successful. In fact four approaches seem to consistently productive:

1. Appealing to the subject’s conscience.
2. Identifying contradictions in the subject’s story.
3. Use of praise or flattery.
4. Offering moral justification and / or psychological excuses.

It is very interesting to note that these four approaches appear to coincide very well with the four dominant personality type interviews that we use in Practical Kinesic Interview & Interrogation®.

The next time you are preparing for an interview or interrogation, mentally create four separate dialogues you can have with your subject using each of these four approaches. Once in the interview room, make an assessment of the most likely personality type of the subject you are interviewing and use one of the four dialogues most appropriate. You should find you’ll get positive results must faster and have a higher admission and even confession rate.