Here, as in the States, the polygraph never made it into court, because it hasn't been judged reliable enough to substitute for or complement human judgement. The debate over such techniques has now being revived by the advent of brain-scanning technologies, such as fMRI, which some scientists believe offer a route to more reliable lie detection.
The Parliamentary Office of Science and Technology (POST) provides MPs with independent, reliable information on scientific issues pertaining to public policy, and it recently issued a report on the latest developments in lie detection. It found that fMRI testing can attain 70% or 80% levels of accuracy. This sounds pretty impressive until you consider - as the report does - that such results are obtained under highly artificial conditions, the most artificial of which being that the subject cooperates. In most criminal cases, of course, you can expect the subject to try and fool or confuse the technology - and fMRI is highly vulnerable to the most banal countermeasures. Simply moving a finger or toe or - very slightly - one's head can completely baffle this expensive machinery, by muddling the results of the scan.
The report also notes that the Ministry of Justice is to carry out a pilot of old-fashioned polygraph testing on sex offenders released on licence. The UK government wants to ascertain “whether use of polygraphs increases the disclosure offenders make under supervision". The answer of course, is yes, but mainly because suspects tend to believe that such machines can read their minds - and so they preemptively 'fess up. The polygraph's effectiveness as an interrogation is itself based on a lie - the lie of its own infallibility. Which raises interesting questions about whether that's a legitimate reason for the government to use it, and whether it might induce as many false confessions as true ones.
The scene above, from The Wire, was based on something David Simon witnessed for real when he shadowed the Baltimore police force in the 1980s, and it shows how pretty much any machine can stand in for an actual polygraph, as long as the suspect is credulous enough to believe in it. (If you're short on time, start about 1"50 in).
(Hat tip: neuroethics and law)
Comments