Patrick Jane lie detection through pulse-sensing
Patrick is "The Mentalist", who helps police solve murders.
The show aired between 2008-2015, and I just started watching it after seeing a few reels/clips on social media.
A logician rivalling Sherlock, plus the mentalism of course.
One skill Patrick frequently showcases is detecting lies by sensing changes in someone's pulse.
Obviously, the show takes (giant) liberties with Patrick's "skills". So I'm not expecting everything Patrick does to be "evidence-based".
But pulse-sensing seems believable to some degree, and I wanted to see what actual science may exist.
If you think about it, what Patrick is doing is basically administering a polygraph test (using his own natural devices). Of course, a polygraph test senses much more than a person's pulse or heart rate.
In any case, as a starting point, it seems instructive to ask "do polygraph tests work" (as lie detectors)?
That's exactly what this 2025 study examines.
It's a fascinating research paper. What the researchers did:
Dow, Jeu, and Watkins present the first published empirical analysis of polygraph reliability. Starting with the universe of cases where an individual was convicted and was subsequently exonerated on the basis of DNA evidence ... the Authors take advantage of a natural experiment that results from the conviction of individuals subsequently determined with near certainty to be innocent. By ascertaining which cases of the wrongfully convicted individuals included a polygraph examination, and by studying how those examinations were interpreted, then, because the individuals are now known to be innocent, the Authors were able to determine the reliability of these polygraph results (which were obtained before the actual innocence of the subjects was known).
And their conclusion?
polygraphs yield unreliable conclusions in approximately 50 to 65 percent of all cases-worse than a coin flip. This failure rate represents a reason for caution in all contexts where polygraph examinations are routinely used, including criminal investigations.
The study gives a few case studies:
Corey Batchelor insisted he had nothing to do with either the robbery or murder of Lula Mae Woods, who was found dead in 1989 in Chicago, Illinois. During their interrogation, police told Batchelor he had failed a polygraph exam. Confronted with this bogus claim, Batchelor confessed to a murder he did not commit. He served twenty-seven years before being exonerated.
Justin Black suffered a similar fate. In 2007, he was charged in West Virginia with the 2002 murder of Deanna Crawford. After maintaining his innocence from the outset, including during a polygraph examination, Black confessed to the crime after being told he had failed the exam. He served eleven years for a crime he did not commit before being officially exonerated in 2021.
In Nebraska, James Dean began to wonder whether he really might have been an accessory to the murder of Helen Wilson. Informed he had failed a polygraph and would face the electric chair if he did not come clean, Dean confessed to participating in a crime he had nothing to do with. He served five years before being exonerated in 2009.
Even a confession doesn't prove guilt.
So, all in all, not so good for Patrick Jane -- even if he could read pulses as good as a polygraph!