|
Whether lie detectors will ever be
adopted on a similar scale in Britain is still a matter of
opinion. At first sight, it appears obvious that any simple,
reliable method of convicting guilty people is valuable, but
recent research sponsored by the U.S. Office of Public Health
not only raises doubts about how lie detectors should be used
but also makes it questionable whether they should be employed
at all.
The point is that, apart from many of the polygraphers being
unqualified, the tests themselves are by no means free from
error, primarily because they discount human imagination and
ingenuity. Think of all those perfectly innocent people, with
nothing to be afraid of, who blush and stammer when a customs
officer asks them if they have anything to declare. Fear, and a
consequently heightened electrical response, may not be enough
to establish guilt. It depends on whether the subject is afraid
of being found out or afraid of being wrongfully convicted. On
the other hand, the person who is really guilty and whose past
experience has prepared him for such tests can distort the
results by anticipating the crucial questions or deliberately
giving exaggerated responses to neutral ones. The success rate
of up to 90% claimed for lie detectors is misleadingly
attractive. If we refer such a figure to a company with 500
employees, twenty of whom are thieves, the lie detector could
catch 18 of them but in doing so would place 48 innocent
employees under suspicion. The problem for the management would
therefore become one of deciding how much industrial unrest they
are prepared to cause in order to eliminate theft. What concerns
research workers even more, of course, is the fact that a
certain number of innocent people are bound to be convicted of
crimes they have not committed.
It seems surprising that a much more effective way of using lie
detectors has not achieved wider currency. The method consists
in asking the subject to read aloud certain statements about the
crime in question. Clearly, anyone who was unaware of the true
facts would make no distinction between saying: "The thieves got
away in a blue Ford" and "the thieves got away in a red Mini".
Only a person involved in the problem would be likely to
register any reaction when he had to read the true statement.
Whether or not he successfully disguised his reaction, this
method would at least make it virtually impossible for an
innocent person to be convicted in his place. In moral terms,
this must surely be the most important point of issue. |
