Apparently, every person lies an average of 1.65 times every day. However, since that average is self-reported, maybe take that figure with a pinch of salt. The truth is, most people are great at lying. The ability to conjure up a plausible alternative reality is, when you think about it, seriously impressive, but it takes practice. From about the age of 3 young children are able to make up false information, at a stunning rate of one lie every 2 hours – though admittedly the lies from a toddler’s wild imagination are relatively easy to identify.
When we lie, brain cells in the prefrontal cortex – the planning, ‘executive’ of the brain – work harder than when we tell the truth. This may be reflected in the physical structure of our brains as well: pathological liars have been shown to have more white ‘wiring’ matter and less grey matter in the prefrontal cortex of their brain than other people. But how can we tell if someone is telling a lie, or telling the truth?
Back in the day – 2000 years ago – in ancient India, people would use the rice test to spot liars. When someone is lying, their sympathetic (‘fight or flight’) nervous system goes into overdrive, leading to a dry mouth. If you could spit out a grain of rice, you were seen to be telling the truth. If your mouth was parched and you couldn’t spit the grain out, you were lying. Since then, several different methods of catching out liars have been used – to varying levels of success.
In several books and films (Harry Potter, True Lies, The Hitchhiker’s Guide to the Galaxy and many more), a ‘truth serum’ is used to elicit accurate information from the recipient. In actual fact, however, truth serums don’t exist. Apart from in fiction, their title is an ironic misnomer. Having said that, scientists have tried for decades to develop a failsafe ‘veritaserum’ in order to catch out liars.
Alcohol has been used as a sort of lie preventor for millennia, as the Latin phrase ‘in vino veritas’ (in wine [there is] truth) demonstrates. Alcohol acts in the brain by increasing the activity of GABA channels, leading to a general depression of brain activity. This has been thought to suppress complex inhibitions of thoughts and behaviours, loosening the drinker’s tongue. However, drinking alcohol doesn’t prevent people giving false information, and it by no means prompts people to tell ‘the truth, the whole truth and nothing but the truth’.
A drug called scopolamine was used to sedate women during childbirth in the early 20th century when a doctor noticed that the women taking the drug would answer questions candidly and accurately. Scopolamine acts on GABA receptors in a similar way to alcohol, and so a person intoxified with the drug is just as likely to give false information as someone who’s had a few stiff drinks.
Barbiturates are sedatives such as sodium amytal that work on the brain in a similar way to alcohol – by interfering with people’s inhibitions such that they spill the beans. Sodium amytal was used in several cases in the 1930s to interrogate suspected malingerers in the U.S. army, but the drug does not prevent lying and can even make the recipient more suggestible and prone to making inaccurate statements.
In the 1950s and 60s, the CIA’s Project ‘MK-ULTRA’ tested drugs such as LSD on unconsenting adults and children. If LSD proved a reliable truth serum, it would be an invaluable tool in the Cold War. The tests showed that LSD would be far too unreliable and unpredictable to use in interrogation.
Despite the repeated lack of success in the search for a ‘truth serum’, scientists have continued trying to develop alternative technologies for busting liars. The polygraph, used by respected institutions including the CIA , FBI and The Jeremy Kyle Show, measures changes in arousal – heart rate, blood pressure, sweating, and breathing rate – in order to detect deception. However, there is a lot of scepticism surrounding polygraphy. In particular, there are several hacks to avoid getting caught out by a polygraph – most notably biting your tongue, difficult mental arithmetic, or tensing your inner anal sphinchter without clenching your buttocks (thanks for that factual gem, QI).
The improvement of brain imaging methods – in particular functional magnetic resonance imaging or fMRI – has extended the scope of detecting liars. On the internet, one might stumble across ‘No Lie MRI’, an American firm that offers a lie detection service for individuals, lawyers, governments and corporations. They claim that this service could be used to “drastically alter/improve interpersonal relationships, risk definition, fraud detection, investor confidence [and] how wars are fought.”
Currently James Holmes, the man charged with injuring 70 and killing 12 at the Batman cinema shooting in Aurora, Colorado, is on trial. The judge has ruled his consent to a “medically appropriate” narcoanalytic interview and polygraph. That is, Holmes could be interviewed under the influence of sodium amytal or other similar drugs in order to determine whether or not he is feigning insanity. The use of these drugs may contravene the U.S. Constitution’s 5th Amendment ‘the right to remain silent’. Clinical psychiatrist Professor Hoge says, “The idea that sodium amytal is a truth serum is not correct. It’s an invalid belief. It is unproven in its ability to produce reliable information and it’s not a standard procedure used by forensic psychiatrists in the assessment of the insanity defence, nor is polygraph.”
The potential benefits of a 100% reliable, valid method of lie-detection are obvious, although there are ethical grey areas that scientists and the legal/ethical community would need to tackle if the technology is ever found. For now I think the evidence for using current lie detection methods, especially for anything more serious than The Jeremy Kyle Show, is far too sparse.
Post by Natasha Bray