Polygraph

The polygraph has been around, in one form or another, for more than 100 years. In 2003, however, the US National Research Council concluded there had been little improvement in polygraph 'science' over this time. The modern polygraph measures physiological responses (rate of breathing, heart activity, blood flow, sweating and movement) in response to questioning. It uses observed changes on print-outs, to assess whether people are responding differently to neutral questions and those, where the individual is attempting to hide information (simplistically described as 'lie detection'). It was consequently interesting to read Ian Sample's account of his brief experience of the technology at the UK's Heaton Mount training course for polygraph operators (https://www.theguardian.com/science/2021/mar/05/there-is-no-bomb-what-i-learned-taking-a-polygraph-test). Sample appeared interested in whether the UK Ministry of Justice's apparent enthusiasm for the polygraph was justified. Currently, the technology is used on child sex offenders to assess whether it is likely they are deviating from 'control orders' (such as staying away from children). Given the claimed success of polygraphs in studies on sex offenders, there are plans to extend such assessments to domestic abusers. Some people would even like polygraphs to be used on terrorism suspects. The Heaton Mount training course is accredited by the American Polygraph Association. Some people find this concerning, as this is a Trade Association (keen to sell the equipment and to further its use), rather than a scientific body. Sample notes that the polygraph has UK enthusiasts (like the people running the training course) and detractors. Quick and relatively inexpensive programmes, with 'simple' answers, tend to be popular with authorities. I tend to agree with Sample's conclusion that 'innocent' people may well get nervous and respond to all questions in a suspicious manner. In other cases, practised liars may remain ice-cool (especially with practise, as there are methods of 'fooling' the tests). If polygraphs are to be used, it must be recognised they will throw up lots of false positives and false negatives. It would be dangerous to rely on polygraphs too much, because it looks like 'science'. Attempts should always be made to confirm their 'conclusions', even if this takes time and patience. Otherwise, miscarriages of justice are likely. Some of the errors could even prove fatal.