Tremors of the Trade

Retired NYPD detective Warren J. Sonne writes for in an article titled, “Tremors of the Trade: Investigative Tool or Troublesome Black Magic?” Excerpt:

Over the past decade, police departments all over this country have lined up to purchase Voice Stress Analyzers. In a country that has placed restrictive rules of law on the police such as Mapp v Ohio (Fourth Amendment exclusionary rule against unreasonable searches and seizures) and Miranda v Arizona (Fifth Amendment right against self-incrimination, and Sixth Amendment right to counsel). My question is, “Are PDs playing with fire?”

I believe that the plain answer is, “yes.”

I think that the first problem comes from the “Pac-Man” generation. Give us a high-tech toy and some practice, and within an hour we will defeat those lying criminals. Once we’ve done that, we can move on to the next level. Hey, CSI solves two or three crimes during their one-hour episodes, don’t they? Well, if they can do itÂ….

There are no quick fixes to criminal investigations, nor are there magic boxes to help detectives figure out who’s lying. There are no shortcuts to competent investigations — at least, there shouldn’t be.

The second problem that I see originates in the many high profile false confession cases that have plagued our profession. The Central Park Jogger case in New York is just one such example. In April of 1989, a young woman was assaulted and raped while running inside of New York’s Central Park. Investigation identified five teenagers as suspects to this crime, and subsequent interrogations produced confessions from four of them. This led to all five being convicted for this crime. In 2002, an unrelated person confessed to this crime, and his confession was coroborrated by DNA. This person, Matias Reyes, claimed that he acted alone. Since there was no corroborating evidence against the five teenagers, other than their confessions, their convictions were overturned.

There are many other cases that have been overturned by the courts involving people, some of them mentally challenged, who have confessed to crimes that they didn’t commit. As a result, many police departments across the country have instituted polices requiring the videotaping of all confessions, with some departments recording all, or nearly all, interviews.

So, do we really need a Supreme Court decision here? Another Miranda? “You have the right to remain quiet and refuse to play the CVSA Game.”

A third issue is, does it work? What is Voice Stress Analysis (VSA), also called Computerized Voice Stress Analysis (CVSA)? The equipment now being produced is in the form of very nice looking computers that allegedly measure “micro-tremors” in the voice. The manufacturers of this equipment claim that these micro-tremors are produced when people are under stress, such as when they are lying. One obvious problem is that stress can and does occur for many other reasons in addition to lying.

Some scientific studies (not all) have verified that these micro-tremors exist and can be measured. Unfortunately, these same scientists and their studies have failed to demonstrate lie detection accuracy using CVSA at anything better than chance (flipping a coin).

I visited the web site of the leading CVSA manufacturer, The National Institute for Truth Verification, but other than their claims that CVSA works as a lie detector, I could find no scientific studies to back it up. What I did find were a half-dozen or so endorsements from police officers who were scattered around the country. Yet, not one these endorsement actually claimed that the CVSA worked as a lie detector. It was called a “valuable tool,” and most of endorsers seemed to like the training program, or the versatility of it, but not one claimed that it was an accurate lie detector.

I remember the Xerox machine being a valuable investigative tool as well. All the detective had to do was push the magic button and out came a piece of paper with the word LIE or TRUTH on it. “What’s your name?” was the first question. “Sam Jones” was the reply. Push the button and out came the answer “TRUE.” “Okay Sam, you’ve done pretty well so far. Now, did you steal your Bill Doe’s bike this morning?” asked the detective. “No,” says Sam.” Push the Xerox button, and here comes the answer, “LIE.”

Some of you may laugh, yet others will remember the utility of this less than scientific procedure. People can be awestruck by the appearance of science. Before the advent of the Xerox machine, people had to use “carbon paper” if they wanted copies. People could certainly be naïve in those days. Well, faced with the scientific appearance of CVSA, people can still be naïve in these days as well. The argument for CVSA seems to be based on the utility of the device, not the accuracy of it.

Sonne is absolutely right. But his criticisms of voice stress analysis are largely applicable not only to voice stress analysis, but to polygraphy, too.

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