{"id":13803,"date":"2018-09-29T01:35:29","date_gmt":"2018-09-29T01:35:29","guid":{"rendered":"http:\/\/www.lifeandnews.com\/articles\/?p=13803"},"modified":"2018-09-30T01:38:12","modified_gmt":"2018-09-30T01:38:12","slug":"is-a-polygraph-a-reliable-lie-detector","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/is-a-polygraph-a-reliable-lie-detector\/","title":{"rendered":"Is a polygraph a reliable lie detector?"},"content":{"rendered":"

Jessica Gabel Cino<\/a>, Georgia State University<\/a><\/em><\/span><\/p>\n

Attorneys for Christine Blasey Ford, the woman who\u2019s accused Supreme Court justice nominee Brett Kavanaugh of sexual assault, released the results of a polygraph test focused on the decades-old incident. They suggest that Ford\u2019s responses to two questions about her allegations were \u201cnot indicative of deception<\/a>.\u201d<\/p>\n

How trustworthy is that assessment and the polygraph technology it relies on?<\/p>\n

People have long yearned for some way to separate truth from falsehood, whether in high-stakes court cases or family kerfuffles. Over the years, inventors have developed an evolving assembly of tools and instruments aimed at figuring out whether someone is telling a lie. They\u2019ve tried to incorporate increasingly more science, but with varying degrees of success. Society has often looked to instruments like the polygraph to inject some objectivity into the detection of deception.<\/p>\n

As a defense lawyer, I\u2019ve had many a client tell me that he or she did not commit the alleged crime. But I\u2019ve never asked a client to submit to a polygraph exam: It\u2019s high risk, low reward, and the results \u2013 while inadmissible in a criminal case \u2013 are unpredictable. Just how reliable is a polygraph at identifying who\u2019s lying and who\u2019s telling the truth?<\/p>\n

Looking for signs of lies<\/h2>\n

Methods of lie detection have progressed from their torture-centric<\/a> roots. Early techniques included subjecting someone to a water test<\/a>: Those who sank were considered innocent, while floating indicated guilt, lies and witchcraft. Neither outcome was good news for the accused. In medieval Europe, an honest man was thought to be able to submerge his arm in boiling water<\/a> longer than a liar.<\/p>\n

Eventually people developed more humane methods, focusing on physiological factors that could be used as arbiters of truth. In the early 20th century, William Moulton Marston \u2013 self-proclaimed \u201cfather of the polygraph\u201d<\/a> \u2013 showed a strong link between systolic blood pressure and lying. Basically, spin a tale and your blood pressure rises. Martson also created the comic book character Wonder Woman, whose golden lasso can extract the truth from those it ensnares.<\/p>\n

In 1921, physiologist John Larson<\/a>, from the University of California, Berkeley, was the first to couple measurements of both blood pressure and breathing, looking at rises and drops in respiration. The Berkeley Police Department adopted his device and used it to assess the trustworthiness of witnesses.<\/p>\n

In 1939, Larson\u2019s prot\u00e9g\u00e9, Leonarde Keeler<\/a> updated the system. He made it compact for travel and added a component to gauge galvanic skin response<\/a>, which measures sweat gland activity that could reflect the intensity of an emotional state. His device, purchased by the FBI, was the precursor to the modern polygraph<\/a>. Later versions were variations on this original.<\/p>\n

\n \"\"<\/a>
\n Sensors detect changes in how the subject\u2019s body reacts to questions from the examiner.<\/span>
\n AP Photo\/Fernando Vergara<\/a><\/span>
\n <\/figcaption><\/figure>\n

Lie detectors today<\/h2>\n

\u201cLie detector\u201d is a broad term. It most often refers to a polygraph, but also applies to a Certified Voice Stress Analysis<\/a>, an fMRI brain scan<\/a>, or even software used to analyze the word choice and variation<\/a> a subject uses when recounting an event. <\/p>\n

What today\u2019s polygraph does is encapsulated in the word itself<\/a>. \u201cPoly\u201d means many or multiple, and \u201c-graph\u201d means to write. The system records several physiological responses \u2013 most often perspiration, heart rate, breathing rate and blood pressure \u2013 and graphs them out visually for an examiner to interpret.<\/p>\n