Most lies are of the white kind, doing nobody harm
and generally making life far easier than it would be if we
all knew what was going on. Other lies are more important,
actually having a distinct purpose. Criminals, adulterers and
spies all need to lie regularly if they are to stay out of
trouble, and some people are paid vast amounts of money to
work out exactly who is telling the truth.
Lies are tricky things. They are difficult to pin down,
having no odour, image or other form of physical
manifestation. The usual way to uncover a lie is to collect
evidence that points to the contrary. The police have to spend
many long hours searching for clues, to piece together the
real story in the face of six different versions from six
different people. Private investigators can make a reasonably
comfortable living sitting in cars outside houses which have
their blinds mysteriously pulled down in the middle of the day
waiting for a fleeting chance to take a conclusive
picture.
Lie Spotting
Alas, no such form of foolproof detection exists. Contrary
to popular beliefs, the famous lie detector is a myth. No
expert or machine yet discovered can definitively spot a lie.
Study after study has shown that lie detectors are a myth.
People who think they can spot a lie do no better than
people who don't think so, who in turn do no better than
chance dictates they should (although a study conducted
entirely on mothers of teenagers may well yield different
results). The only humans who do show lie detecting abilities
are people with a type of aphasia (the inability to produce
speech) which prevents them from understanding speech. This is
thought to be because there are subtle changes in people's
faces, between when they are sincerely expressing an emotion
and attempting to replicate an emotion, which aren't noticed
by most people because they are concentrating too hard on the
spoken words. The only other group who are better than average
at detecting lies are secret agents, which is unsurprising
considering their lifestyle.
That is not to say that there is no way to detect lies.
There are pointers which can be picked up if the observer
knows what to look for. However, often these signs can be
misinterpreted. Signs change from one individual liar to the
next, and the motive behind a lie may affect how comfortable
the teller is; and the more comfortable they are, the less
likely they are to be caught out.
Types of Lie
Lies can be categorised in many different ways, but a
widely held view is that there are four types of lie:
-
Pro-social - Lying to help someone else.
-
Self-enhancement - Lying to make yourself look
better while not hurting another.
-
Selfish - Lying to personally benefit at the
expense of another.
-
Anti-social - Lying to deliberately damage
another.
Simple Signs of Lying
The type of lie, and whether it is in keeping with the
liar's character, dictates how apparent the signs of lying
are. Occasionally they are extremely obvious, especially when
the liar is feeling guilty.
Obvious signs include:
-
Over denial - Repeating protests of innocence.
-
Stuttering - Stumbling over words without natural
fluency.
-
Hand Wringing - Fiddling, rubbing, picking and
playing with the fingers and hands while talking.
-
Eye Contact - Unwillingness to make or never
breaking it.
However, the majority of people intending to tell a lie
fabricate their story long beforehand and become comfortable
with it, and so rarely get caught out so easily. Equally, many
of the signs indicated may also simply be signs of nerves due
to shyness or discomfort with a new situation.
Subtle Signs of Lying
There are of course more subtle signs which most people
miss, and which can affect even word-perfect liars. These
include:
-
Over formal speech - Use of long words, painfully
correct grammar and the full forms of words or phrases that
would normally be shortened, suggesting a scripted speech
rather than natural conversation.
-
Very few gestures and no pointing - As physical
movement illustrating something being described are a quite
common and natural activity.
-
Justification - Attempting to justify every detail
with lengthy explanations
-
Disparity - Mismatch between tone of voice and
expression.
People who are used to detecting lies develop an instinct
towards the more obscure signs, perhaps without even
consciously noticing them. Most people, however, have a great
deal of difficulty working out when someone is telling the
truth. Which is why there are so many attempts to make a
foolproof machine for catching lies.
Detecting Lies with
Machines
The industry name for a lie detecting machine is a
polygraph. 'Poly-' means many or lots and '-graph'
refers to writing or the recording of information. This is
essentially what a polygraph does, measuring and recording
information from multiple sensory inputs that can be
interrupted to show how comfortable a person is at a certain
moment, or series of moments, in time.
Polygraphs work on the assumption that people telling lies
are uncomfortable. Maybe not very much, but nevertheless they
feel differently to when they're telling the truth, resulting
in changes to heart rate, breathing, perspiration and so
forth. A polygraph test assumes that these are involuntary
changes to your body which always occur when you lie. This
alone means that pathological liars often fool lie detector
tests because they show no change when they tell a lie.
However, taken together, it is assumed there is enough of a
change in the readings between truth and lie to be able to
make a definitive decision.
A polygraph interview will usually take several hours, and
takes place in a room where only the interviewers, who like to
be called forensic psychophysiologists1, and the subject are present,
although others can be watching from behind one-way mirrors.
First the examiner and the subject have a basic chat, where
the examiner calibrates the equipment, and tries to put the
subject at ease. The actual test comes later when the examiner
asks several relevant questions and also some control
questions to check that the responses are still the same.
Analysis of the questions takes place afterwards.
There are two types of wrong polygraph readings. False
positive is when a subject has tested positive for a lie,
although they are in fact telling the truth and is the
commonest type of error. False negative is when a subject has
been acquitted of lying, even though they are guilty.
Cheating
Polygraph readings, however, are not solid evidence for
anything. The very act of having to defend their character may
agitate a perfectly innocent person to the extent where the
machine records that they are lying. There are also various
ways to cheat the polygraph:
-
The examinee may bite their tongue, dig their nails into
the palm or do something else that causes pain and
significant discomfort just before they answer every
question. The pain should prompt a greater physiological
response than a lie would, so it would drown out the
response to the lie, and would mean that the response to the
test would be the same every time.
-
The examinee may use deodorant on their fingertips if
they know they will be measured for sweatiness. This absorbs
the sweat and so fixes the results.
-
The subject may use a sedative, to dull their body's
response to the point where the difference between the
reactions to truth and lies is so small as to make the test
inconclusive.
Legality
Polygraph tests are an ambiguous area of the law. Depending
on where you are, there are laws regulating their use. Many
courts will not accept evidence from a polygraph test, because
there is too big an area of uncertainty - although lawyers are
allowed to mention them in defence of their client if they
wish. Some places consider them an infringement of civil
rights and ban people from making others take them. If they
are to be used by companies, there are laws relating to the
questions that can be asked, and no employee can be forced to
take one, although the company is free to draw whatever
conclusions they wish from that refusal. Polygraphs are very
widely used in the United States, with the federal government
being the largest user of them, while the police use them to
assist in their investigations, even though they are not
always used as actual evidence.
Many people are opposed to polygraph tests, and there are
many organisations which oppose them, such as AntiPolygraph.org. They do this because they
claim they are fundamentally inaccurate. Statistics show a
range of 70% to 90% accuracy depending on who delivers the
statistics and whether they count 'inconclusive' results as
wrong results, or merely discard them since they gave no
evidence one way or the other. There are scientists who point
out that polygraph tests do not in fact detect lies, merely
register the physical state of the subject at the time, which
is open to myriad outside influences. There are also those in
the legal industry who object to the fact that polygraphs can
be used as evidence by a defendant, but not the prosecution,
while some believe that polygraph tests are immoral and a
violation of human rights.
Defenders of polygraphs, like the American
Polygraph Association argue that people with nothing to
hide wouldn't be so opposed to them, and point out that they
are very rarely used on their own - they are usually presented
in conjunction with other evidence. There is also the fact
that they are improving all the time with computer programmes
which can analyse the voice for tremors, which is far less
intimidating than being attached to wires. In addition, new
research suggests that brainwaves change when lies are told,
paving the way for even more accurate technological lie
detectors of the future.
Detecting Lies with
Chemicals
Truth inducing drugs are a staple part in the plot of many
Hollywood espionage movies. They offer a very convenient means
to ease the plot on its way. But is there any credibility
behind the romantic ideal?
Well, thiopental sodium, which is trademarked under the
name 'Sodium Pentothal' by Abbott Laboratories is an
anaesthetic with side-effects similar to truth serums of the
movies. Allegedly, when a small enough dose is administered
the patient does not lose consciousness, instead entering a
very relaxed state. Individuals in this state are far more
open to suggestion than normal and lose many of their
inhibitions. This in turn makes them more likely to voice what
they are thinking without considering their words first.
However, they keep their self-control, and would not do or say
anything against their nature. This would make it a poor tool
in detecting deliberate lies, since if the subject is
unwilling to tell the truth they will not be forced to do so
by the effects of the drug.
Conclusion
Life would be far easier for some people if there were a
foolproof method for spotting lies. However, whatever method
we use there is always the possibility that our assumptions or
estimations will be incorrect. Clearly, it would be far easier
still if people simply didn't lie in the first place. But then
how would you keep children from learning the truth about
Santa Claus and the Tooth Fairy?
Related BBC Links
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