Lie-detector tests don’t work (Terrorist convicts to face lie detector tests after release, 21 January). Not only is there no scientific basis for conducting the tests, there is also no evidence the results are reliable. This is the official position of the American Psychological Association. Rather, the lying is inferred by the human operator, based on observing physiological parameters under questioning. But there is no evidence such parameters relate to lying. As one expert put it, what the polygraph measures is anxiety. Convicted terrorists are just the kind of people who can lie without measurable anxiety.
If you put Boris Johnson in the machine and asked him questions, do you think it could distinguish between him lying and telling the truth? I would bet against him feeling any anxiety when he lies. Or any politician for that matter. This is a stunt based on Hollywood tropes, not a rational response to terrorism.
Michael Attwood
Cambridge
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