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Sunday, 6 January, 2002, 08:31 GMT
A brief history of lying
The conventional polygraph-style lie detector
The truth, whole truth and nothing but...
News of a possible scientific breakthrough in the quest for a reliable lie-detector throws the spotlight on the age-old problem of sorting out lies from truth.

The business of sifting truth from lies is literally heating up.

In the United States scientists claim to have come up with a lie detector that uses a super-sensitive thermal imaging camera to spot minute heat rushes around the eyes.

We are reaching the point where we will have no alternative other than to use truth serums on the suspects we are holding

FBI source quoted by the Washington Post
At the same time, the US authorities are contemplating the use of "truth serums" to obtain information about terror groups.

The problem of working out who is lying and who is telling the truth - especially in the fields of international diplomacy and the legal system - is as old as civilisation itself.

But the idea that a person's truthfulness can be detected, regardless of what they are actually saying, may be not much more than a throwback to ancient ideas of trial by ordeal.

In English medieval courts truth was tested by ordeals of fire and water, on the basis a truthful person would be protected by God.

"Believe me, fire wouldn't do me any good"
Someone suspected of lying would have to carry a red-hot iron bar for nine paces. Alternatively he could opt to walk across nine red-hot ploughshares.

Either way, if the suspect was burned then this was proof that he was lying and so could be promptly hung.

Other courts went in for trial by water. In the ultimate "no-win" situation, the person accused of lying was put into a sack and thrown into a pond.

If the accused sank this showed he was innocent, but he might well drown anyway. If he floated this was taken proof that he was lying and he would be hanged.

Such practices were ended in 1215 by edict of the Latern Council.

By the 1600s the idea arose that the truth of any statement could be arrived at by the means of detailed questioning and the application of scientific and logical reasoning to what was being said.

Jeffrey Archer
"You look a bit flushed, Jeffrey"
Modern legal conventions of cross-examination and the presumption that somebody is telling the truth unless it can be proved otherwise "beyond reasonable doubt" date from this time.

The philosopher Descartes wrote that "the power of distinguishing the true from the false, which is properly speaking what is called good sense or reason, is by nature equal in all men".

Trying to work out whether somebody was lying was a matter of questioning, debate and the clash between different points of view based on the gathering and analysis of evidence.

The 19th Century saw a reversion to ideas of truthfulness and lying as moral conditions embedded in the unique personality of the accused person.

Peter Mandelson
Is that lying? Peter Mandelson told an "untruth" according to colleague Jack Straw
The new "sciences" of phrenology - measurement of "bumps" on a person's skull - and psychology - led to the idea that lies could be detected by looking at physical symptoms.

It was eventually argued by phrenologists that pathological liars and "criminal personality" could be determined by measuring the shape of a person's skull. Psychologists concentrated on of past personal life, "personality type" and even the content of someone's dreams.

Phrenological "evidence" of criminal personality type was presented in Victorian murder trials and used to secure conviction of "guilty types" whose evidence could not be relied upon.

The search for "scientific" ways of spotting liars moved from bumps on the head to brain chemistry, with the search for a "truth serum" drug.

Barbiturates including scopolamine, sodium amytal and sodium pentothal were given to suspects in the hope that drugs could somehow rewire the brain, making it incapable of telling a deliberate lie.

The "medicine" had the intended effect of causing the victim to lose control over what he was saying. But the result was normally an endless stream of drug-addled gibberish rather than "the truth".

In 1963 the US Supreme Court said "serum-induced confession" was in effect a form of torture and the practice was ruled unconstitutional.

The latest attempt at scientific detection of truth and falsehood comes, fashionably enough, in the application of sophisticated electronics to the problem.

Makers of the latest lie detector machine - which measures supposedly tell-tale changes in temperature around the eye sockets when somebody is telling a deliberate untruth - claim a "success rate" of 83% in detecting liars.

But whether it will prove any more reliable that conventional "polygraph" lie detectors, which rely on sensors to detect breathing rate, pulse, blood pressure and perspiration, remains open to question.

See also:

02 Jan 02 | Sci/Tech
Spotting the face of deception
01 Nov 01 | UK
What gives a liar away?
03 May 00 | Health
How to spot a liar
16 Mar 01 | UK
MI5 ponders lie-detectors
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