After a few simple warm-up questions, Jack hits Greg with "have you ever watched pornographic videos?" Greg has questioned the accuracy of the polygraph, but on this question he freezes.

The camera focuses on the polygraph needle going crazy. How does Greg answer this question when he wants to ask Jack if he can marry his daughter?

Greg was right to question the accuracy of a polygraph to detect lies. The machine measures several physiological indicators including blood pressure; pulse; respiration and skin conductivity to determine if the participant is telling a lie.

They are used as an interrogation tool by several agencies, such as the FBI; CIA and LAPD but most jurisdictions don't accept the results in a court of law.

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The movies, on the other hand, would have you believe the results are infallible. Quite the opposite is true.

Assessments by scientists have concluded that polygraphs are highly inaccurate and may easily be defeated by countermeasures.

The polygraph dates back to 1921 and I am sure it won't surprise you to learn that technology has improved in the last 101 years.

Researchers at Tel Aviv University believe they have finally invented a better mousetrap.

This lie detection method uses a smart sticker which contains electrodes. It is applied to the face of a participant and measures miniscule activities of muscles and nerves in the face.

Ask a serious poker player and they will assure you that, just by observing their opponent's face and mannerisms, they can tell if a player is bluffing.

I don't know if anyone has ever tested the accuracy of those claims, but this latest research says that maybe there is some truth in that. Despite our best efforts, maybe our face is giving away more than we would like.

What I found particularly interesting was how different indicators were present in different test subjects.

Some liars twitched a cheek muscle. Others had eyebrow movements. Still others had a combination of a cheek and an eyebrow in a specific sequence. There is also work being done on the reactions in relation to the size of the lie.

When my wife asks "do these jeans make me look fat" and I give the only acceptable answer of "no" then my face may not give too much away. On the other hand, when a criminal is asked if he was involved in a bank robbery, it may be harder to be deceitful.

The body reacts differently because the consequences of being caught out are dramatically different.

At this early stage of the research, the success rate is only 73 per cent, which is better than a polygraph, but still not good enough for any court system to adopt this process.

As with so many modern technologies though, time and artificial intelligence will quickly improve the outcomes.

As more test subjects are examined and more facial movements are analysed and then all of that data is fed into an advanced algorithm, the accuracy will quickly improve.

I think it will still be some time before we see a lie detection test being part of a legal argument in the courtroom, but wouldn't it be interesting to have this type of technology connected with a live worm graph on screen the next time we see a political debate aired on TV?

Tell me if you think you could trick technology and get away with a lie at ask@techtalk.digital.

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