David Lykken and the Polygraph Myth

David T. Lykken, a psychologist who did pioneering research and public education on the limits and abuses of polygraph testing, died last week at age 78.

With exceptional clarity he demonstrated that the polygraph is not a “lie detector” but simply a recorder of physiological responses to verbal stimuli. And, he explained, there is no set of physiological responses that corresponds uniquely to deception.

That does not mean the polygraph is worthless. There is empirical evidence to support its use in the investigation of specific incidents, where “guilty knowledge” of particular details may be usefully revealed by the polygraph.

“The use of the [polygraph] by the police as an investigative tool, while subject to abuse like any other tool, is not inherently objectionable,” Lykken wrote.

(Not only that, “It seems reasonable to conclude that whether O.J. Simpson did or did not kill his wife could have been determined with high confidence using a Guilty Knowledge Test administered within hours after he was first in police custody.”)

On the other hand, he said, the use of the polygraph for security screening of personnel, as is commonly done by U.S. intelligence agencies, cannot reliably achieve its purported goal of identifying spies or traitors and in many cases becomes counterproductive.

“I think it is now obvious that polygraph testing has failed to screen out from our intelligence agencies potential traitors and moles. On the contrary, it seems to have served as a shield for such people who, having passed the polygraph, become immune to commonsense suspicions.”

Lykken produced a body of work that is prominently cited in every bibliography of polygraph-related research. And he addressed the interested public in a highly readable 1998 book called “A Tremor in the Blood” (an allusion to Defoe), which is full of colorful observations as well as analytical rigor.

So, for example, he reports that Pope Pius XII condemned polygraph testing in 1958 because it “intrude[s] into man’s interior domain” (Tremor, page 47).

And “when Bedouin tribesmen of the Negev desert were examined on the polygraph, they were found to be far less reactive than Israeli Jews, whether or Near Eastern or European origin” (page 273).

Dr. Lykken was profiled in a September 20 obituary in the New York Times.

It is a sign of our times that the scientific critique of polygraph testing has gained almost no traction on government policy. To the contrary, the use of the polygraph to perform the sort of screening that Lykken termed a “menace in American life” is actually on the rise.

“From FY 2002 through 2005, the FBI, DEA, and ATF conducted approximately 28,000 pre-employment polygraph examinations” as well as tens of thousands more for other purposes, according to a major new report from the Justice Department Inspector General.

See “Use of Polygraph Examinations in the Department of Justice” (pdf), September 2006.

Characteristically, the new Inspector General report did not even consider the question of the polygraph’s scientific reliability.

In particular, as George Maschke of AntiPolygraph.org told CQ Homeland Security, the Justice Department report failed to grapple with a 2002 finding of the National Academy of Sciences that “[polygraph testing's] accuracy in distinguishing actual or potential security violators from innocent test takers is insufficient to justify reliance on its use in employee security screening in federal agencies.”

Aldrich H. Ames, the former CIA officer whose years of espionage against the United States went undetected by the polygraph, reflected on the mythology of the polygraph in a letter that he wrote to me from federal prison in November 2000.

No Responses to “David Lykken and the Polygraph Myth”

  1. Anne Brewbaker October 31, 2007 at 8:37 AM #

    Everyone should read Dr. Lykken’s article to further or begin their education on constitutional rights.
    Polygraph testing will work only on the subjects who believe that a machine can detect lies and/or truth. If people would get informed on the myth of this machine, much of the money invested to perfect it so it can frighten people even more, could be spared for true scientific research.
    The purpose of the so-called “lie detector” test is to instill fear to get a confession or an admission. It has no scientific value. It’s a “voodoo” machine and those who understand that are poor candidates for the–test.! So Law Enforcement Agencies want you to believe and respect this machine; but the fact is that polygraph cannot differentiate between anxiety caused by criminal actions and anxiety arising from other burdens or problems. There is no scientific study to support the claim of lie detection. It is pure quackery. But it scares peoples as they believe in it, so it WORKS.!!!
    However an examinee cannot reply except by yes or no. When the suspect is being asked to answer to the relevant questions pertinent to the offense, he cannot take the 5th since he must answer yes or no. And that seems to be a violation of constitutional rights.
    We also must remember that the police are overwhelmed with crime. The polygraph is just a tool very convenient to try to solve their many burdens.It’s up to every individual to get educated and make their voice count.
    Anne Brewbaker Dallas.

  2. Anne Brewbaker. Dallas January 25, 2008 at 3:13 PM #

    When I hear that a person did not get a job or that an individual was released from prison after 15 years of incarceration due to a wrong conviction, following a negative polygraph test, I really get upset, very upset because such a situation is unacceptable.

    The test results rely solely on the interpretation of the examiner, therefore it is the test’s validity and reliability that are in question.The polygrapher works on the assumption that he can read our minds. Polygraphy will remain in place because it creates fear, and people do believe in it blindly without second thought.

    What is needed here, is ACCOUNTABILITY and RESPONSIBILITY from the polygraphers and/or the organizations that employ their services. Then, and only then we will see more logic, more caution and more sagacity in judgment, because there will be a price to pay for some terrible mistakes impacting the life of our citizens.
    We need to petition Congress about this particular area of accountability for deception exposure, for the good of all.
    -Anne Brewbaker Dallas.

  3. Deep Thought March 6, 2011 at 10:03 AM #

    It seems obvious to me that a psychopath or actor would ‘breeze’ such a test. Blind faith in anything is dangerous. How do those in high places manage to hammer so many square pegs through round holes based upon their beliefs? The image is everything to them those that can see the real code behind the illusion are few indeed.