Polygraph tests don't work as lie detectors and they never have. It’s time to stop pinning our hopes on pseudoscience.

Pedro_P

Spoiler alert: Polygraph test results are now processed on a computer, no needle required.
Deposit Photos
▼ The polygraph, historian Ken Adler wrote, has long been treated as “America’s mechanical conscience.” People turn to the machine in times of crisis, demanding clarity from the biomedical readouts, hoping something as simple as a heartrate can distinguish what’s true from what’s false. Individuals with evidence on their side still feel compelled to take these tests to appease the larger public—and those with the evidence stacked against them hold up polygraph results as if they trump the obvious truth.
Yet, for almost as long as there have been polygraph tests, there has been evidence that the machines don’t really work. “There is no lie detector, neither man nor machine,” the first empirical review of the machinery concluded in 1965, a view that has been supported by every scientific publication on the topic since. Except in very rare (and often worrisome) circumstances, the results of a polygraph are not admissible in court in the United States. And the test’s overall uselessness has been publicly revealed time and again: Green  River Killer Gary Ridgway passed a  lie detector testin 1987, delaying justice for almost two decades.
So why do we keep strapping in? It seems our endless search for the truth makes us vulnerable to a few pernicious lies.
How it (doesn’t) work
Since its inception almost 100 years ago, the polygraph has remained largely unchanged. Really three tests in one, the polygraph concurrently monitors cardiovascular, respiratory, and electrodermal outputs of the human body. A blood pressure cuff monitors the bloodflowing in and out of your heart, and a second apparatus measures pulse. Rubber tubes placed on the chest track air entering and exiting your lungs. Finger plates track the sweatseeping through your skin.
These biometric results are accurate, says John Synnott, a lecturer in investigative and forensic psychology at the University of Huddersfield. But it’s the interpretation—the leap from the physical data to the psychological motive—that so often fails. “When people say the polygraph doesn’t work, I’d call [them] on that,” Synnott says. “The polygraph always works, because all the polygraph does is measure physiological output.” But, he says, it’s never “detected” a lie. (▪ ▪ ▪)

► Please, read the full note here: Source

harpreetsembhi

I concur... This is the wrong perception!! Lie detecter can be beaten successfully.