The urban legend goes like this: Police wire the gullible crook up to a copy machine, put a colander on his head and say the contraption is a lie detector. Intimidated, the crook confesses.
Police say the latest lie-detecting gizmo – one that looks for vocal tremors in recorded conversations – is also eliciting confessions.
But many scientists, including Washington University psychologist Mitchell Sommers, say the voice analysis devices are little more than $10,000 colanders. In distinguishing liars from truth-tellers, flipping a coin works better, according to a study Sommers performed.
“It’s beyond my imagination why anyone would buy one of these devices,” Sommers said.
Yet at least 1,400 law enforcement agencies have. Missouri ranks second, behind Florida, for the number of agencies that have bought a Computer Voice Stress Analyzer, sold by the National Institute for Truth Verification, a Florida company that pioneered so-called voice stress analysis. There are at least 29 agencies in the St. Louis area that use them.
Polygraphs assume that lying causes measurable changes in a person’s breathing, pulse, blood pressure and sweat. Similarly, voice analysis assumes that lying causes stress, which in turn causes tiny telltale tremors and other modulations in a person’s voice.
Sommers says the devices are pretty good at detecting stress. But whether that stress indicates lying is another question. There’s the stress associated with lying, he said, and there’s also the stress of being an innocent person in an interrogation room.
University of Chicago psychologist John Cacioppo says the devices depend on consistent reactions, when individuals can have different physical responses to lying. One person’s gut might churn, while another’s voice might quaver.
Moreover, he adds: “We tend to treat lies as if they are all the same. There’s a spontaneous lie, well-rehearsed lie, a lie for greater good, a lie for individual gain.”
A company called V, based in Chicago, claims its voice analysis algorithms identify more than just deception. The company says its “layered voice analysis” devices can detect excitement, comfort and concentration.
“In some cases, (it) can pick up sexual arousal,” said spokesman Jayson Schkloven. Through a subsidiary, the company markets a “love detector” to consumers.
In a study commissioned by the Department of Defense Polygraph Institute, Sommers found that an earlier version of V’s technology picked up lies less than a third of the time, even in a high-stress mock crime scenario.
Some scientists say the polygraph, on the other hand, can identify liars at rates as high as 80 percent. A 2003 National Academy of Sciences study reviewed dozens of papers and unpublished studies. It concluded that the polygraph had many flaws, but could still find liars at rates better than chance (50 percent).
As far as voice methods, the study’s authors found “little or no scientific basis” for its use as an alternative to polygraphy.
“It’s not that it’s all nonsense, but the hype is so great that you have to be skeptical,” said Stephen Fienberg, a Carnegie Mellon University statistician and the lead author of the academy study. He says he hasn’t found a “single, credible, scientific” study that would cause him to believe the devices worked well.
The manufacturers respond by saying academic studies will always underreport the devices’ success because mock scenarios can’t mimic the stress of criminals trying to avoid arrest for serious crimes.
“If there’s no consequence, there’s no stress,” said National Institute for Truth Verification executive director David Hughes. “You’d think if you catch bad guys, everyone would be happy.”
Sommers said that increasing the stakes could increase the detectable stress. But he said most academic researchers wouldn’t be able to perform such tests for ethical reasons.
While academics debate their legitimacy, the devices appear to be catching on in the insurance arena. They’re used in Britain to screen out fraudulent claims. The U.S. insurance industry has been hesitant to use them for fears of alienating customers, said James Quiggle, spokesman for the Coalition Against Insurance Fraud.
“But there are rumors that some insurance companies are quietly using (voice analysis) to handle routine claims calls,” he said.
According to V, Illinois-based Safeway Insurance Group has completed a pilot study in a California call center using V’s devices.
Kirkwood Police detective Thomas Joseph said he has used his voice stress device hundreds of times, mostly on pre-employment screenings for police candidates.
He readily admits that it’s not a lie detector.
“This is merely a tool,” said Joseph, who is on the board of directors for the National Institute for Truth Verification. “There isn’t an ideal tool out there that’s going to say, ‘John Doe, you’re lying.'”
Everybody, he says, is offering a new and better mousetrap – they come and go. Upon joining the Kirkwood department in 1994, he found an old voice-based system collecting dust in a storage closet.
The device, made in the late 1970s by now-defunct Dektor, is contained in a locked suitcase. It contains a plastic unit, covered in chrome switches and dials and a spool of graph paper that would show the results of the voice analysis. Joseph said the machine didn’t work very well, and eventually fell into disuse.
“They invested all that money in it and it died,” he said.
Area law officers use voice analyzer
The National Institute for Truth Verification says more than 1,400 law enforcement agencies have bought the $10,000 voice stress analysis device it sells. These area agencies use the devices:
Breckenridge Hills Police
Des Peres Police
Eastern Mo. Correctional Center
Franklin County Drug Task Force
Franklin County Prosecutors Office
Franklin County Sheriff’s Dept.
Jefferson County Sheriff’s Dept.
Kirkwood Police Dept.
Lincoln County Sheriff’s Dept.
St. Ann Police
St. Louis County Police
Webster Groves Police
University City Police
These agencies did not return messages. The National Institute for Truth Verification says it has sold them the devices:
St. Louis Community Release Center
Maryland Heights Police
Richmond Heights Police
St. Louis Police
Warren County Sheriff’s Dept.
List compiled by Matthew Fernandes of the Post-Dispatch