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New technologies
Novelty lie detector a hit among techno buffs
By Iris Cheng
Iris Cheng
Senior Counsel Michael Lunn.
Last year, a Korean company manufactured the world’s first portable polygraph, better known as a lie detector. Even though polygraph results are inadmissible in Hong Kong courts (see accompanying sidebar), the device was immediately introduced by Ashop.com.hk into the Hong Kong market, where it has become a popular novelty, according to the distributor.
According to Associate Professor Chan Tin Cheung of the Department of Psychology at The Chinese University of Hong Kong, a polygraph examines the level of arousal of a subject.
“A person usually becomes more aroused during lying. A polygraph basically works by detecting the expected changes of a person when emotionally disturbed or aroused.
“The physiological changes are complex. They generally include sweating, increased heart rate, pupil dilation and hormone secretions.”
The portable polygraph, dubbed Truster, operates under similar principles.
Toby Tse, the web master for Ashop.com, said, “The core technology of the device is voice analysis.”
According to Mr. Tse, the human voice is a complex instrument, and it is not easy for people to manipulate their voices.
The $880 device can analyze vocal segments gathered over the phone, taken from the TV or radio shows, or face-to-face conversations.
The manufacturer claims that the human voice consists of six global levels: The textual level is the words people speak; the identifying level is the unique element in every person’s voice; the intonation level is the way people express themselves.
There are then three levels not under voluntary control: The emotional level indicates emotions such as excitement; the cognitive level indicates the amount of conflict or agreement with a spoken sentence; the physiological element indicates the stress, physiological alertness and general physiological condition.
Truster examines the emotional, cognitive and physiological patterns in the subject’s voice.
Mr. Tse said, “The machine first records the voice of an individual speaking casually in the usual manner, establishing a standard defined as ‘true’. Vocal segments of the same person in different situations are then compared with this standard. Deviations mean that the person may be lying.”
Before the device can be put to use, a sample of a person’s voice is first needed.
The device will produce a computerized analysis of a voice sample’s speech flow, indicating the particulars of emotional, cognitive and physiological elements within that voice.
When used to test for lying, comparison with the standard is made, and the result is displayed immediately on the screen.
The result is one of nine categories: “Truth”, “Outsmart”, “Excitement”, “Subject is not sure”, “High Excitement”, “Avoidance”, “Extreme Excitement”, “Inaccuracy” and “False statement”.
Besides detecting deception, the device can also measure the level of stress. Hence, the resultant measurements not only help to distinguish between truthful or false reports, but also provide indications of the mental, psychological and physical states of the subject.
Therefore, proper interpretation of results is crucial.
There are three main indications that show a person is lying.
When a person is stressed, confused and excited all at the same time, one is likely to be lying.
But there are some people who manage to lie convincingly without any of the above symptoms.
This is because they do not feel that their lying is wrong at all.
On the other hand, an honest person may also get stressed, confused and excited while trying to recall the facts.
Therefore, it is recommended by the manufacturer that common sense be used to evaluate the results.
The best way to do this is by considering the specific context of conversations.
Said Mr. Tse: “I’ve tried it before with my friends. The accuracy rate is about 70 percent, lower than the 84 percent as claimed by the Korean maker.”
Prof. Chan also agreed that at present, polygraph results are not very accurate.
“All polygraphs assume lying leads to stress, anxiety and arousal. But this may not always hold true.
“In fact, there are ways to defeat polygraphs. Taking and holding a deep breath to keep yourself from becoming aroused is an example.”
He also added that there are other detective agents that are more reliable.
“Devices for the purpose may monitor the nerve impulse from the lie centre of human brains. EEG, the electromagnetic waves from the brain, may also be examined.
“But there are technological problems in doing so at present.
“Once these are solved, there’s a chance for an absolutely accurate polygraph to be produced.
“After all, everything is possible.”
Iris Cheng The portable polygraph, Truster
Hong Kong courts do not accept polygraph resultsBy Iris Cheng
Lie detector results are not admissible in Hong Kong's courts.
One of the most important uses of the polygraph is to help provide clues in criminal investigations.
But the use of the polygraphs by police and the admissibility of results in courts are still controversial.
The practice varies from place to place.
In Hong Kong, polygraphs are not used by the police. The courts also do not accept their results as evidence.
Senior Counsel Michael Lunn said, “Evidence has to be supported with solid foundations. It must pass reliable scientific tests and gain general scientific acceptance.
“Lie detecting is similar to handwriting and fingerprinting analysis. There are experts who are permitted by the court to express their professional opinions and will interpret these kinds of test results. The judge will decide whether or not to admit the results.”
But the problem is that these experts have no standard qualifications.
“They are experts only because they are experienced in the field,” said Mr. Lunn.
There have even been cases where experts disagreed with each other. In any case, the final decision is left to the judge.
“But even if a court admits the expert opinions, the test results can only be used as a subsidiary reference.
“The most important evidence is still the witness,” said he.
Different countries vary in their legal practices regarding polygraph results, but, generally, polygraph results are seldom admitted by courts.
According to Mr. Lunn, in Israel, the military police and the security services frequently make use of the polygraph during their investigations.
Besides, to help justify the arrest or release of a suspect, judges there sometimes admit polygraph results.
In England, the Royal Commission on Criminal Procedure consider the use of the polygraph as one of the means to reduce the risk of false confessions.
In the United States, though there are more than 5,000 polygraph examiners, examination results are generally not admissible as evidence, even though there have been exceptional cases in the past.
In Western European countries, the use of polygraphs is rare and sometimes even prohibited.
For example, in France, it is a criminal offence to use polygraph.
In West Germany, the use of polygraphs is considered a violation of constitutional rights.
