Polygraphs are widely viewed as unreliable indicators of lies, despite the Trump administration’s increasing reliance on the tool to weed out agitators in the federal government.
Popularly known as lie detector tests, polygraphs monitor bodily responses such as blood pressure, changes in a person’s breathing, and sweating on the palms. In recent weeks, top Cabinet officials have used the tactic to root out leakers from federal departments.
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However, experts say the polygraph is not everything it is cracked up to be.
Most psychologists agree that there is little evidence that polygraphs can accurately detect lies, according to the American Psychological Association, which has recommended against using lie detector tests in investigations. The APA argues that polygraphs are a more accurate indicator of anxiety than they are of lying.
“The accuracy of polygraph testing has long been controversial,” researchers wrote. “An underlying problem is theoretical: There is no evidence that any pattern of physiological reactions is unique to deception. An honest person may be nervous when answering truthfully and a dishonest person may be non-anxious.”
Polygraphs are typically prohibited from being used as evidence in courts. In the 1998 case United States v. Scheffer, the Supreme Court decision made polygraph evidence inadmissible in a court-martial proceeding, ruling that “there is simply no consensus that polygraph evidence is reliable.”
Leonard Saxe, a psychologist at Brandeis University who has conducted research into polygraphs for decades, told Vox that “there’s no unique physiological sign of deception. And there’s no evidence whatsoever that the things the polygraph measures — heart rate, blood pressure, sweating, and breathing — are linked to whether you’re telling the truth or not.”
But the measure is still broadly used, including by the federal government’s top agencies, government employers, and law enforcement, because “it doesn’t matter whether the test actually works, just that it’s perceived as effective.”
Advocates believe polygraphs are useful as a prop — part of what Saxe characterized as the “theater” of interrogation in comments to the outlet.
“If the examiner does the theater well, and tricks the subject into believing that his or her lies can be detected, they might confess,” he said.
The American Polygraph Association stands by its position that scientific evidence supports the validity of polygraphs when “conducted in accordance with APA Standards of Practice.” The APA carried out research in 2011 that vindicated its belief, producing findings that the combination of all validated psychophysiological detection of deception techniques, excluding outlier results, produced a decision accuracy of 87%.
Members of President Donald Trump’s Cabinet, including FBI Director Kash Patel, Homeland Security Secretary Kristi Noem, Defense Secretary Pete Hegseth, and Attorney General Pam Bondi, have discussed and deployed polygraph testing to root out leakers in their departments.
“The Department of Homeland Security is a national security agency,” DHS spokeswoman Tricia McLaughlin told the Washington Examiner. “We can, should, and will polygraph personnel. Under Secretary Noem’s leadership, DHS is unapologetic about its efforts to root out leakers that undermine national security. We are agnostic about your standing, tenure, political appointment, or status as a career civil servant—we will track down leakers and prosecute them to the fullest extent of the law.”
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Some government agencies and law enforcement agencies are employing a new lie-detection tool called EyeDetect, according to Converus, the device’s developer. The DHS and CIA are among the agencies Converus is lobbying to adopt EyeDetect, per the Intercept.
The DHS and FBI declined to comment on whether they use EyeDetect. The Washington Examiner reached out to the CIA and the Defense Department for additional information but did not receive a response.