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Stormy Daniels’s polygraph test doesn’t reveal anything.

The porn actress, whose real name is Stephanie Clifford, reportedly took a videotaped polygraph test in 2011 for Life & Style magazine when it investigated her allegations that she and Donald Trump had an affair early in his current marriage to Melania Trump, according to The Wall Street Journal. That tape is now part of her lawsuit against Trump over a $130,000 nondisclosure agreement she signed before th 2016 election.

According to the polygraph, Daniels was “truthful” in responding “yes” two questions: “Around July 2006, did you have vaginal intercourse with Donald Trump?” Around July 2006, did you have unprotected sex with Donald Trump?” The New York Daily News claimed this “shows Stormy Daniels was truthful about having ‘unprotected’ sex with Donald Trump.” NBC News reported, without skepticism, that the “Lie Detector Test Shows Stormy Daniels Truthful About Trump Affair.

But polygraph tests don’t really detect lies. As Vox’s Joseph Stromberg noted in 2014, “lie-detector” tests actually measure anxiety in the test-taker, which may (or may not) be related to whether that person is telling the truth. Accordingly, polygraph tests are inadmissible in American criminal trials and the Supreme Court determined in 1998 that there “is simply no consensus that polygraph evidence is reliable.” Both the National Academy of Sciences and the American Psychological Association have concluded that there is little scientific research supporting the tests’ accuracy.

Thanks to its frequent appearances in popular culture, however, the device’s mystique endures. It’s certainly possible that Daniels had an extramarital affair with Trump in 2006. (If nothing else, the videotaped test from 2011 proves her version of events predates Trump’s political career.) Giving credibility to a device that hasn’t earned it isn’t the way to prove her story, though.