Category: Lying

The latest verdict on using brain imaging for lie detection

Excitable tabloids, technophile lawyers and gullible entrepreneurs have all spent the last few years salivating over the prospect of functional brain imaging delivering us the first form of truly scientific, objective lie detection. Not so fast.

Most research that’s tested the potential of functional brain scanning for lie detection has compared brain activity between lying and honest conditions by averaging signals across whole groups of participants – no use for real life. Now George Monteleone and colleauges have taken a representative paper from this literature and thoroughly examined its potential for spotting individual liars.

The paper they examine was by Lhan Phan and colleagues in 2005 and involved fourteen participants having their brains scanned whilst they either told the truth or lied about playing cards in their possession. Consistent with several other similar papers, Phan’s study showed differential activity in a raft of brain areas when people lied versus told the truth, especially frontal regions involved in working memory and deliberate effort.

Monteleone’s team took the brain activity of each individual in Phan’s study and compared it with the averaged activity of the other 13 participants to see if the “lying areas” identified at the group level were also extra active when that specific participant was lying.

At the group level, 16 brain regions showed differential activity when lying compared with telling the truth. The brain area that most resembled a true “neural signature” for lying was the medial prefrontal cortex (mPFC). Seventy-one per cent of participants showed heightened activity in this region when they were lying compared with telling the truth. This is better than chance, but far from perfect – really no different from the classic polygraph.

Also, just like the polygraph, brain imaging suffers from the problem of balancing specificity with sensitivity. For example, if the threshold for significant mPFC activity is lowered, then the number of participants showing notable lying-related activity in this region increases, but so too do the number of false alarms – that is, participants who show activity in this region when they’re telling the truth. In real life legal settings, these “false positives” could mean innocent people going to jail or worse.

What’s more, Monteleone’s team warn that it’s highly unlikely mPFC activity is a true neural signature for lying. Just as there are many reasons why our pulse might race and our palms get sweaty (thus triggering a polygraph), there are many potential excitors of mPFC activity, including self-consciousness and thinking about other people’s mental states.

This also raises the problem of cunning criminals devising simple ways to foil the brain scanner. A participant who performed complex mental arithmetic during truth and lying conditions, or who concentrated on the examiner’s mental state throughout a scan, would likely spoil any neat comparison of truth and lying conditions.

The problems don’t end there. Monteleone’s group further showed that for some lying participants, specific brain regions that appeared to be activated by lying were in fact really part of a far larger spread of brain activation that probably had nothing to do with lying at all. There’s also the fact that the playing card lying paradigm is so simple and insipid compared with real-life lying. Also, the researchers observed that a minority of participants showed idiosyncratic brain responses to lying, out of keeping with the general group-level patterns. And finally, there are socio-cultural issues. Problems with language and the cultural appropriateness of deception could both massively distort a person’s brain response to lying versus truth-telling.

“…[A]lthough fMRI may permit investigation of the neural correlates of lying,” the researchers said, “at the moment it does not appear to provide a very accurate marker of lying that can be generalised across individuals or even perhaps across types of lies by the same individuals.”

Monteleone, G., Phan, K., Nusbaum, H., Fitzgerald, D., Irick, J., Fienberg, S., & Cacioppo, J. (2009). Detection of deception using fMRI: Better than chance, but well below perfection. Social Neuroscience, 4 (6), 528-538 DOI: 10.1080/17470910801903530

Link to related Wired news story: Evidence from fMRI lie-detection was used in a courtroom for the first time earlier this year.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

BOLD-faced lie detection

You wouldn’t know it from the claims of companies like No Lie MRI, but we’re a long way off being able to use brain scans to detect reliably whether a person is lying or not. Nonetheless, cognitive psychologists are busy beavering away in the background, testing the ways that brain activity varies when people lie compared with when they tell the truth. One such study has just been published, claiming to be the first to investigate deception in the context of face recognition.

Sujeeta Bhatt and colleagues scanned the brains of 18 participants undergoing a simple task designed to simulate a police line-up. The researchers compared brain activity across three conditions: when the participants pointed out truthfully which face from three they’d seen earlier; when they lied and pointed to a new face rather than the one they’d seen earlier; and finally a condition where all the faces were new but the participants lied and pretended to have seen one of them before.

No single brain area was active when the participants lied compared with when they told the truth. However, a network of frontal and parietal regions were more active in the lying conditions. This network included the dorso- and ventro- lateral prefrontal cortices, the superior frontal gyri, and the anterior cingulate gyrus, all of which are found at the front of the brain. These areas are known to be involved in working memory, response selection and error monitoring. In the parietal lobe, the precuneus – an area known to be involved in visual imagery- also showed increased activity during lying.

“It is possible that the frontal and parietal area activation seen in the current study is a result of the complex interplay of working memory, response inhibition, sustained attention, and mental calculations necessary for our subjects to make a deceptive response,” Sujeeta Bhatt and her colleagues said.

However, they further acknowledged that like other studies in this field, their findings are limited by the fact that their participants were not under anything like the kind of pressure that is normally associated with lying in real life. Also, don’t forget studies like this one are looking at average group differences in lying versus truth-telling conditions, rather than studying an individual, as would presumably be required most often in real-life settings. That said, this study makes a worthy contribution to an emerging field that piece by piece will surely one day soon lead to a brain-based lie detection system – watch this space!

ResearchBlogging.orgBhatt, S., Mbwana, J., Adeyemo, A., Sawyer, A., Hailu, A., & VanMeter, J. (2009). Lying about facial recognition: An fMRI study Brain and Cognition, 69 (2), 382-390 DOI: 10.1016/j.bandc.2008.08.033

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

There are plenty of popular science articles about the potential of brain-based lie detection. Here’s a sample:

A positive kind of lying?

Telling lies about our past successes can sometimes be self-fulfilling, at least when it come to exam performance. That’s according to the New York Times, which reports on studies by Richard Gramzow at the University of Southampton and colleagues.

Their research has shown that, when asked, many students exaggerate their past exam performance, and that those students who do this tend to go on to perform better in the future.

What’s more, a study published in February (rtf doc) showed that when these exaggerators are interviewed about their past academic performance, they don’t show any of the physiological hallmarks associated with lying, but rather their bodies stay calm. It’s almost as though this is a different kind of lying, aimed more at the self, with the hope of encouraging improved future performance.

As the New York Times says:

“…such exaggeration is very different psychologically from other forms of truth twisting. Touching up scenes or past performances induces none of the anxiety that lying or keeping secrets does, these studies find; and embroiderers often work to live up to the enhanced self-images they project. The findings imply that some kinds of deception are aimed more at the deceiver than at the audience, and they may help in distinguishing braggarts and posers from those who are expressing personal aspirations, however clumsily.”

Link to New York Times report
Link to rtf of study showing that students stay calm when exaggerating.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Adults are unable to tell when children are lying

With their wide eyes and innocent hearts, you might think it’s easy to tell when a child is lying. Oh no it isn’t. Not according to Leif Stromwall and colleagues, who found adults were useless at detecting when children were lying.

Thirty children aged between 11 and 13 were told they were going to be interviewed about one event that had really happened to them, and about another that they’d never experienced (an earlier questionnaire identified which life experiences the children had actually had). The children’s task was to talk about both events as if they had experienced them both.

So next the children were interviewed about two such experiences (e.g. the time they were bitten by a dog, or the time they found a dead bird) by one of three female researchers who were blind to which experiences the children had and had not really experienced. Half the children were given two minutes to prepare for talking about the experience they’d never had, the others had to make up their account on the spot.

The children’s parts in the interviews were video-taped and played to 60 undergrads (average age 26 years) whose task was to identify which accounts were truthful and which were fabricated. Overall, the undergrads were correct 51.5 per cent of the time – no better than chance. They were slightly better at spotting the unprepared made up accounts, identifying 55.6 per cent of these.

It’s no wonder the undergrads were so poor at spotting the children’s lies – the children seemed to anticipate their lie-detection strategies. For example, the most commonly used cue the undergrads said they looked for was a lack of detail in the children’s accounts, but meanwhile the children’s most commonly cited strategy for appearing convincing was to add detail to their accounts by drawing on information they knew about from other people’s experiences. The undergrads also said they had looked for signs of nerves, while the children said they had tried to stay calm.

Children are often witnesses in criminal cases so these findings have serious, practical implications. “It should be acknowledged that detecting deception in children is a difficult task, perhaps as difficult as detecting adults’ lies”, the researchers said.

Stromwall, L.A., Granhag, P.A. & Landstrom, S. (2007). Children’s prepared and unprepared lies: Can adults see through their strategies? Applied Cognitive Psychology, 21, 457-471.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Just how good are police officers at detecting liars?

By Emma Barrett, of Psychology and Crime News and the Deception Blog.

We had just sat through a presentation by a proponent of the Reid Technique, a potentially psychologically coercive method of persuading a suspect to confess, used widely in North America (although not in the UK). The North American police officers, in the majority at this international conference a couple of years ago, loved it. British police delegates and we psychologists shifted uncomfortably in our seats.

Next up, an esteemed American psychology professor, who gave a tour de force of his specialist subject: false confessions. In the Reid Technique, once an officer is convinced that a suspect is guilty, the psychological coercion begins. The professor argued that this might cause a vulnerable and innocent suspect to make a false confession: much depends on whether the officer is right when they believe that a suspect claiming innocence is lying. The speaker cited a recent meta-analysis (DePaulo et al., 2003) to make the point that, according to psychological research, there are no reliable cues to deception, and added that other research implies that police officers are not very good at spotting liars. The Brits and psychologists smiled again.

But I was still uncomfortable. DePaulo’s review is great, but if you take a look at the list of studies included, you’ll find that the evidence is almost wholly from studies of how Western students behave when deceiving in relatively low-stakes situations. Research on whether
law enforcement officers can detect deception usually involves them sitting in front of video clips of, you guessed it, Western students. So, satisfying as it might be to trounce the Reid guys, shouldn’t we wait for more ecologically valid studies before we tell officers they are no good at detecting deception?

This is why I’ve chosen a recent paper from Aldert Vrij, Samantha Mann and their colleagues at Portsmouth University, published earlier this year in Applied Cognitive Psychology. Not because it’s the best paper of the last three years in forensic psychology, but because it’s the latest in a series of studies that are becoming increasingly ecologically valid and relevant to law enforcement concerns. An issue that I think is crucially important.

In this study, the materials were clips from real suspect interviews where ground truth was known, the stakes were high, and the participants were experienced police officers. A welcome step forward from the usual student-based studies.

The officers’ task was to judge four sets of clips of liars / truth tellers on four different occasions. Their total accuracy (four tests combined) was 72 per cent. This is an improvement on the usual 50-60 per cent hit rate typically found in deception studies (e.g., Vrij, 2000). Officers were equally good at detecting truth (70 per cent accuracy) and lies (73 per cent). However, on average officers believed that they had only performed at chance level, and were “overly modest about, rather than overconfident in, their performance”.

So perhaps police officers aren’t as bad at detecting deception as some might have you believe. We’ve a long way to go yet – for instance, there’s plenty of evidence that would-be lie catchers often rely on rigid cues, including signs of nervousness, which could be displayed by an innocent person who is anxious about being believed (Ekman, 2002). We need to know more about the circumstances under which this occurs – and how to stop it. But the sorts of studies that Vrij et al. are now conducting are, I think, the right way to go. Conducting such research is more challenging than doing experiments with students, but it’s a crucial step towards really helping law enforcement deal with deception. Finally, I’d like to give a big cheer to Kent Police who facilitated the research. Collaboration between academics and practitioners is by far the best – perhaps the only – way to go forward here.

DePaulo, B.M., Lindsay, J.J., Malone, B.E., Muhlenbruck, L., Charlton, K. & Cooper, H. (2003). Cues to Deception. Psychological Bulletin, 129, 74–118.

Vrij, A., Mann, S., Robbins, E. & Robinson, M. (2006) Police officers ability to detect deception in high stakes situations and in repeated lie detection tests. Applied Cognitive Psychology 20, 741–755.

Vrij, A. (2000). Detecting lies and deceit: The psychology of lying and its implications for professional practice. Chichester: John Wiley and Sons.

A case of pseudologia fantastica, otherwise known as pathological lying

The events that led to Lorraine being incarcerated on a secure forensic unit at age 22 are mind-boggling. It began when she reported to police that a colleague had been sending her death threats in the post. Then about a year later she reported to police that her best friend Abby had developed a lesbian infatuation with her and was stalking her. Two weeks later, her friend Abby appeared to have abducted Lorraine at knifepoint and was subsequently charged and imprisoned. Fast forward another year and Lorraine now reported receiving death threats from her fiancé’s ex wife, and soon after that she blamed her fiancé’s three-year-old son for the starting of two fires in relatives’ homes.

The thing is, there were no death threats, Lorraine had made it all up. She had persuaded her best friend Abby that by appearing to abduct her, she would actually be doing Lorraine some kind of favour. And she set the fires that she accused the three-year-old of starting.

According to Cheryl Birch and colleagues, Lorraine has pseudologia fantastica – a disorder that is characterised not only by the quantity of lies, but also by their fantastical quality. The lies are typically harmful to the liar and are not part of a manipulative plan with a clear objective in mind. Instead they are motivated by internal psychological desires – to boost self-esteem or characterise oneself as a hero or victim. The person with pseudologia fantastica often struggles to distinguish between fiction and reality, but does not experience true delusions and does not have an organic memory impairment. Consistent with this, Lorraine did eventually confess to everything she’d done.

The authors concluded that through better understanding and more awareness of cases like this “…some of the exceedingly costly medical, legal, and social consequences often associated with it can be avoided. [In Lorraine’s case] improved awareness of pseudologia fantastica may have hastened the administration of justice and helped avert some of the attendant social tragedy”.

Birch, C.D., Kelln, B.R.C. & Aquino, E.P.B. (2006). A review and case report of pseudologia fantastica. The Journal of Forensic Psychiatry and Psychology, 17, 299-320.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

How lies breed lies

Lies breed because we’re more likely to tell lies to people who have lied to us. That’s according to James Tyler and colleagues who found telling multiple lies of exaggeration (e.g. “I got a first class degree at university”) is more likely to mean you will be lied to in return, distrusted and disliked, than if you tell lies of underestimation (e.g. “Berlusconi only gifted me £150,000”).

Tyler’s team showed 64 undergrads a video of another student being interviewed. The participants were given a sheet of facts about the student (presented on university headed paper, and ostensibly gathered from the student’s admission interview to the university) so they could tell whether he was lying on not in the video. In fact the student in the video was a confederate of the researchers, and five versions of the video were made, featuring varying levels of honesty.

Afterwards each participant was secretly filmed while he/she briefly met the student who they’d just watched being interviewed. Then the participants were debriefed and asked to point out any lies they had told to the interviewee student.

Participants who’d watched a version of the video in which the interviewee had told several lies of exaggeration were more likely to report having lied to him when they subsequently met, than were participants who watched a version of the video in which the interviewee always told the truth, only told lies of underestimation, or only told one lie of exaggeration.

Unsurprisingly, participants who watched a version in which the interviewee told multiple lies of exaggeration also tended to say they liked him less and found him less trustworthy.

“When people are lied to they may consider a requisite amount of reciprocal deception as a legitimate and called for response”, the researchers concluded. They said this finding could be interpreted in support of the negative norm of reciprocity “in which people tend to ‘reciprocate in kind’ to others who mistreat them”, or it might instead reflect a form of the chameleon effect “in which people non-consciously alter their behaviours to match those of interaction partners”.

Tyler, J.M., Feldman, R.S. & Reichert, A. (2006). The price of deceptive behaviour: Disliking and lying to people who lie to us. Journal of Experimental Social Psychology, 42, 69-77.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.