Lie Detectors – do they really work?

19th April 2019 | Uncategorized

Before we get into this month’s blog on Lie Detectors here’s a link to a Short Story for you. Please note this is not Science Fiction, but does have a small paranormal content. Hope you enjoy.

The Emu and the Orange

Lie Detectors – do they work?

This month’s blog is all about lie detectors and whether they are useful or not. They are primarily used in the fields of criminal investigation or maybe in areas where truth is paramount to the investigator eg. a claim of seeing a UFO or of having a close encounter. Fortunately, we do not all have Pinoccio’s problem. If we did, the human race would be well and truly extinct by now, overburdened and extremely top heavy to the point where we could do little else but sit in the soil and grow ever-expanding noses.

What is a lie detector?

A polygraph, popularly referred to as a lie detector test, is a device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person is asked and answers a series of questions.

The proposal is that the interviewee’s measured responses are different if they are lying or telling the truth. As far as I am aware, however, there are no specific physiological reactions associated with lying, making it difficult to identify factors that separate liars [especially good ones] from truth tellers.


Lie detection goes back quite a long way. The polygraph was invented in 1921 by John Augustus Larson, a medical student at the University of California, Berkeley and a police officer of the Berkeley Police Department. Further work on the device was done by Leonarde Keeler.

As Larson’s protégé, Keeler updated the device by making it portable and added the galvanic skin response to it in 1939. His device was then purchased by the FBI, and served as the prototype of the modern polygraph.

Conducting a test

When the polygraph test starts, the questioner asks three or four basic questions to establish a normal standard for the person’s signals. Then the critical questions being tested by the polygraph are asked. The person’s signals are recorded on moving paper.

A polygraph examiner can check the graphs and can see whether the vital signs changed significantly on any of the questions. In general, a significant change (such as a faster heart rate, higher blood pressure, increased perspiration) indicates that the person may be lying.

When a well-trained examiner uses a polygraph, he or she may be able to detect lying with high accuracy. However, because the examiner’s interpretation is subjective and because different people react differently to lying, a polygraph test is not perfect and can be fooled.

Sometimes a person applying for a job will have to undergo a polygraph test (for example, certain USA government jobs with the FBI or CIA require polygraph tests).


Polygraph testing has generated considerable scientific and public controversy. Most psychologists and other scientists agree that there is little basis for the validity of the procedure. Courts have repeatedly rejected the use of polygraph evidence because of its inherent unreliability.

Nevertheless, it is sometimes used to try to assess the veracity of suspects and witnesses, and to monitor criminal offenders on probation. Polygraph tests can also be used by individuals seeking to convince others of their innocence and, in a narrow range of circumstances, by private agencies and corporations.

The polygraph is also measuring physiological reactions that are associated not just with lying but also with being nervous—a common feeling one might experience when being interrogated.

The Future of lie detection

Despite current skepticism, lie detection methods are still being explored.

One of these is the Converus EyeDetect station, which by capturing imperceptible changes in a participant’s eyes – measuring things like pupil dilation and reaction time – aims to sort deceptive humans from genuine ones.

Released in 2014 by Converus, ‘EyeDetect’ is promoted as a faster, cheaper, and more accurate alternative to the notoriously unreliable polygraph. By many measures, ‘EyeDetect’ appears to be the future of lie detection—and it’s already being used by local and federal agencies to screen job applicants.

And then there are real time brain activity scans.

A suspect is read words related to a crime while their brain is being scanned. A computer analyses the data and informs the examiner if the suspect’s memory holds information about the crime that only the perpetrator could know. The guilty could be clearly identified and the innocent would be set free. You have the right to remain silent would not matter anymore.

It’s not science fiction. The technology and knowledge to scan your brain for the truth is already here and it is improving rapidly.


Without a better theoretical understanding of the mechanisms by which deception functions, development of a lie detection technology seems highly problematic. However, as technology advances, it is not beyond the limits of credibility to envisage that the accused and witnesses in a trial may have to wear ‘truth helmets’. And then, of course, judge and jury could very well be in the ‘hands’ of a computer. You can take that extrapolation even further, but I’ll leave that up to the reader.


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