Age: 78. Americans John Larsen and Leonard Keeler devised it in 1921 to measure the "emotional effort" involved in lying.
It's less of an emotional effort than serving a prison sentence, I gather. Yes, but lying makes you sweat, palpitate and display other give-away signs. With the right equipment to read them, your emissions will betray you.
I thought only America held with that kind of pseudo-science? Not any more. Last week, trials started in Birmingham with a view to introducing the test to Britain. Probation officers called it potentially "helpful" in the war against crime.
Aren't lie detector tests unreliable? You're thinking of Sharon Stone cheating in Basic Instinct. In real life, they have an impressive track record.
Such as? Louise Woodward passed one in her murder trial (it was deemed inadmissible). The CIA uses them to screen recruits.
The CIA? Now there's an organisation not known for lying. Easy. It doesn't test your disposition to truthfulness, just whether you are lying about a specific event, like passing O-level Spanish or shooting a man in Dallas.
But is it any good? 97% accurate according to some data. The US department of defence once said, "without the polygraph as an investigative tool, a number of espionage cases never would have been solved."
I hear there are a lot of investigative tools in the CIA. Will you drop it, already? The lie detector acts as an "artificial conscience" which is harder to fool than a criminal psychologist, being a neutral organ.
Speaking of organs, why don't our own secret services use the test? GCHQ considered it, but shrank from rousing the civil liberties lobby. In France, polygraph testing is an administrative offence.
Do say: "I have a heart condition that makes me naturally jumpy."
Don't say: "That machine had it in for me from the moment we met."
Not to be confused with: reliable evidence.
