National News
Polygraph tests controversial but still used
February 06, 2015 posted by Steve Brownstein
Despite arguments surrounding polygraph use and accuracy, the tests are still administered by police departments across the country, and locally, in criminal investigations and pre-employment.
“It’s a controversial topic because the science really isn’t accepted by the public,” said Richmond County sheriff’s Sgt. Michael McDaniel, who has been an examiner for five years.
McDaniel said the public is much more receptive to DNA evidence instead.
Opponents of polygraph technology say it’s a good indicator of anxiety, but it is not a good indicator of whether someone is telling the truth.
There are few good studies to help settle the disagreement. According to the National Research Council, test trials are flawed and don’t accurately reflect real-world emotions. The American Psychological Association has recommended against polygraph tests in employee screening or investigations.
States have their own laws on when a polygraph is acceptable, however.
District Attorney Ashley Wright said that, as a general rule, polygraphs are not admitted in court. That includes testimony about asking someone to take one, offering to take one or having taken one. Police can’t force anyone to take the test unless it’s a requirement as part of probation, which is the case for some Georgia sex offenders.
The one exception is if both parties stipulate to the admissibility of the test, which can be agreed on before or after the test is taken, Wright said.
GBI special agent in charge Keith Sitton said such stipulated polygraphs are not as rare as some might think.
“The idea behind exclusion of the polygraph is that it is considered scientifically unreliable,” Wright said, “but they can still provide some value to the investigation.”
The officers who use it daily are staunch supporters of its usefulness and effectiveness.
“I quit being surprised,” Sitton said of the results he has seen over the years.
Sitton, who has been an examiner since 1996, said that although he’s always been a supporter, he’s seen the technology change and adapt throughout his career, increasing its validity. The American Polygraph Association continues to update technology and methods, he said.
The version on which needles run across paper has been shelved in favor of a fully digital one. Seat and foot pads have been added to measure other movements, such as fidgeting, which can correlate with lying.
“I have 100 percent confidence in it,” McDaniel said. “I know it works because I’ve seen it work.”
His first exam was an eye-opener, he said. He was testing an upstanding, educated “family man” who had been accused of a sex crime against a teenager. From the outside, it seemed unlikely that the man would fit the crime, but the polygraph showed the opposite.
“My mouth dropped (at the results),” he recalled. “I could not believe what I was seeing.”
Presented with his “failed” test results, the suspect broke down in tears and wrote out a full confession.
“Since then I’m 100 percent positive it works,” McDaniel said. “I see the need for the polygraph and the uses for the cases we have.”
In 2014, the Richmond County Sheriff’s Office conducted 99 pre-employment tests and four for investigations. The Columbia County Sheriff’s Office conducted 93 for pre-employment and 41 for investigations. The GBI, which serves about 200 law enforcement agencies in Georgia, conducts about 2,000 each year.
“There are multiple uses for it,” said Columbia County sheriff’s Lt. Chris Railey, who has been an examiner for three years.
The process begins with pretest, in which the examiner sits with the test subject, and discusses the test and stresses the importance of answering honestly and answers any questions from the subject.
Then the subject is hooked up to several sensors to monitor autonomic arousal. Rate and depth of respiration are measured by two pneumographs wrapped around the chest. A blood pressure cuff monitors cardiovascular activity. Skin conductivity, or sweat response, is measured by electrodes attached to the fingertips. All of the rates are monitored by computer.
In pre-employment tests, police are looking for “an honest candidate” and question about previous detected and undetected crimes.
A test attached to an investigation is wholly different.
It can be used for several purposes: finding guilt or innocence, or locating a weapon or body. It also helps officers determine which direction to take a case. Police could point to a map and ask if a body or weapon is in that particular area. If the sensors trigger a response in a certain area, then police know where to start looking.
“If you have multiple people who have committed a crime, then at times we can use polygraph to narrow that down and quickly clear people of that crime,” Railey said. “A lot of times people will volunteer to take them to clear their names.”
Some Web sites claim to be able to help people pass a polygraph test, but local authorities scoff at the idea.
“We see the same Internet everybody else does, so the things people talk about, we’re more than prepared for,” Railey said.
Some sites claim that sticking a tack in your shoe or biting the inside of your cheek can sway the results and create an inconclusive test.
“If you put a tack in your shoe, the only thing you’re going to do is hurt yourself,” McDaniel said.
