Lie Catchers Stand by Their Polygraphs

Christian Toto writes for the Metro section of today’s (29 June 2006) Washington Times in “Lie catchers stand by their polygraphs.” The article is cited here in its entirety, interspersed with commentary:

    Detective Leonard Keeler developed the first lie detector — or polygraph — test in the 1930s, and the machines used today are not very dissimilar from that first model.

While in January 1931 Leonard Keeler did receive what may be the first U.S. patent (485 kb PDF) for an instrument used as a lie detector (the application for which he submitted in 1925), William Moulton Marston was using a blood pressure recording device as a lie detector as early as 1917. And John Larson was administering lie detector “tests” in Berkeley, California in the early 1920s.

    Even the best liars can get tripped up by their own bodies as the devices detect changes in blood pressure, breathing rate and perspiration levels, which could indicate a person is being less than honest.
    Although some people can say they “beat” the polygraph on occasion, experts say it can’t be done regularly.

Polygraph operators are the wrong “experts” to ask about countermeasures, as they have the most to hide. Simple, easy-to-learn countermeasures to the polygraph are readily available. And no polygrapher has ever demonstrated any ability to detect them.

    The science may seem simple, but it’s far from foolproof. That’s why polygraph tests are not admissible in court and researchers are looking into brain-imaging technology for the next-generation lie detector.

Actually, polygraphic lie detection is not a “simple science.” It is not science at all.

    Howard Miller, head of Miller Consulting Services in Falls Church, says today’s tests are used primarily in the security industry, such as with clients operating armored-car divisions. Polygraph testing also is used in military scenarios and other intelligence areas.
    For years, Mr. Miller and his peers administered polygraph tests using analog signals, much like the medium in which most television signals once were sent. The modern polygraph, like music and television, has gone digital.
    “The computers are very sensitive,” says Mr. Miller, who began using analog systems in the early 1980s but since has switched to digital testing. “There are things it’s reading that examiners are missing sometimes.”
    Reston resident John Sullivan, a 31-year veteran of polygraph testing for the U.S. military and author of the book “Of Spies and Lies: A CIA Lie Detector Remembers Vietnam,” says, “The basic process hasn’t changed at all.
    “We have computerized instruments now that are helpful, but the actual process of running a test is the same,” Mr. Sullivan says.

Sullivan is correct. Polygraphy has not substantially progressed in decades.

    Typically, two tubes filled with air wrap around the person’s chest and abdomen to measure respiration levels. A standard blood pressure cuff around the arm gauges heart-rate fluctuations. Two galvanometers, or finger plates, are attached to the person’s fingers to measure the skin’s ability to conduct electricity. Hydrated, or sweaty, skin does not conduct electricity as well as dry skin.
    If the movies have taught us anything, it’s that lying during a polygraph test causes the equipment’s needle to arc wildly in response. The results are rarely that dramatic, Mr. Sullivan says, not to mention that the digital devices no longer require mechanical devices such as the quivering, ink-laden needle.
    The new equipment also enables the administrator to read the responses in order of the degree of reactivity for more simple comprehension.
    Mr. Sullivan says the next wave of lie detectors could link directly to our brains. Neurologists are working on ways to connect brain-wave activity to lying, he says.
    “I really think that has a lot of potential, but we still have a way to go,” he says, adding that initial research shows that brain-wave changes occur when a person twists the truth.

Actually, brain-wave changes (P300) has shown little if any potential for lie detection. Rather, where it has shown promise is for the detection of concealed information.

    Former Harvard Medical School faculty member Lawrence Farwell dubs a similar process “brain fingerprinting.” This method seeks out brain-wave fluctuations once a person is given a cue related to the information about which he or she may be lying.

Dr. Farwell’s brain fingerprinting technique aims at the detection of concealed information, not lie detection.

    Polygraph tests have their skeptics, and they are legion — visit for a measure of the movement.

Indeed, it is not just that is skeptical of polygraphy. Polygraphic lie detection has been roundly rejected by the scientific community. The only remaining debate pits those who don’t yet understand that it’s junk science against the growing number of people who do.

    Lourdes Griffin, director of the Washington Hospital Center’s outpatient behavioral health service, isn’t convinced the devices can help reveal liars. The machines try to record indicators that typically reveal discomfort, but for whatever reason, “everyone responds differently,” she says.
    “We’re so individual. Any of those stress reactions … could trigger a different stress response in someone else,” she says.
    One person might get nervous near an attractive woman, while another could exhibit stress reactions when standing in front of a large crowd, she says. A sociopath might not exhibit any outward signs of stress from lying, she adds.
    Among the biological reactions to stress is an increase in oxygen levels to the brain to let the person deal with the stressor in question.
    “But are they linked to lying? I don’t know,” she says.
    William Chittenden, president of the Nokesville-based Virginia Polygraph Association, says a subject telling a lie might not trigger all three of the polygraph’s main measurement systems.
    “Some examiners don’t like to deal with the breathing patterns, but it can be helpful,” Mr. Chittenden says. “I like to look at all of them. There’s information in all the channels.”

There may well be “information” on all the channels of the polygraph instrument, but none of it provides any clear indication of whether a person has spoken the truth.

    Sometimes the person being tested is medicated or took drugs thinking it could help them cheat the test.
    “People can be on medication, and they’re still testable. Others may be really not testable if their physiology is so slowed down,” he says.
    The polygraph test isn’t the only way people are trying to separate fact from fiction.
    Clay Shields, an associate professor of computer science at Georgetown University, says a voice analyzer offers a low-tech approach to lie detection. These voice stress analysis tools, which do not need wires or any other connection to the person being interrogated, can detect levels of stress in the voice.
    “It’s inaudible to humans,” Mr. Shields says. “Some people are marketing them as lie detectors over the telephone, and others talk of using them in airport security screenings.”
    The gadgets measure fluctuations in voice frequency levels, which some connect to dishonesty patterns.

No voice stress analyzer has ever been demonstrated to reliably detect detection. The most financially successful marketer of a voice stress analyzer, the National Institute of Truth Verification, which peddles the “Computer Voice Stress Analyzer,” has admitted in court that its device “is not  capable of lie detection.”

    Even polygraph administrators admit some people beat the system, while others insist it can’t be done consistently.
    Mr. Miller says people can be trained to alter some biological activities such as heart rate, but even that takes several minutes to achieve, a window of time a polygraph questioning won’t permit.
    Besides, “when people are altering their biological responses, it shows in the test,” he says.

Miller is being less than honest here. Heart rate is easily increased within seconds, not minutes, using simple techniques (such as performing mental arithmetic timely with the “control” questions) that leave no tell-tale signature. For more on how anyone can fool the polygraph, see’s free e-book, The Lie Behind the Lie Detector (1 mb PDF).

2 thoughts on “Lie Catchers Stand by Their Polygraphs”

  1. Two points on “increasing heart rate taking minutes:
    1. Heart rate is not measured in typical polygraph. Rather, blood pressure is measured.
    2. More importanly, the most quantifiable and sensitive measure is the phasic electrodermal response or GSR. This occurs from about 2 to 5 seconds following question onset, and can be readily increased with by a big intake of breath, or thinking exciting thoughts.

  2. Please note that the quote presented from me is accurate, and that I am only talking about voice-stress devices being marketed and that there has been talk of using them for security screening. I do not make any claims as to the accuracy or sensitivity of any type of lie-detection device, and believe that errors in detection will significantly impact honest people.

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