Why brain-based lie detection is not ready for "prime time"

We are in a new and interesting legal world. Although to date, no US court cases have used brain-based lie detection techniques as evidence, several cases have sought such evidence and settled out of court. fMRI is the most frequent type of brain-based lie detection technology, with two companies, Cephos and No Lie MRI providing this service in the legal domain. There have also been attempts made to use EEG for deception detection. Notably, such a technique was used in part to prosecute a young woman for murder in India in 2008.

I am far from the first to point out that this technology is highly exploratory and not accurate enough to be used in the court of law. My goal here is to outline a good number of the reasons this is the case.

9. We do not know how accurate these techniques are. Although the two aforementioned companies boast lie detection accuracy rates of 90%+, these cannot be independently verified by an independent lab as the methods used by these companies are trade secrets. For example, there are few peer-reviewed studies of the putative EEG-based marker of deception, the P300, and most come from the lab that is commercially involved with a company trying to sell the technique as a product. Interestingly, an independent lab studying the effect of countermeasures on the technique found an 82% hit rate in controls (not the 99% accuracy claimed by the company), and this was reduced to 18% when countermeasures were used!

8. In the academic literature, where we do have access to methodology, we are limited to testing typical research participants: undergraduate psychology majors (although see this). For a lie detection method to be valid, it would need to be shown as accurate in a wide variety of populations, varying in age, education, drug use, etc. This population is not likely to be skilled in deception as a career criminal might, and it has been shown that the more often one lies, the easier it is to lie. Most fMRI-based lie detection techniques are based on the assumption that lying is hard to do, and thus requires the brain to use more energy. If frequent lying makes lying easy, then it could be the case that practiced liars don't have this pattern of brain activity.
     Although a fair amount has been made lately about WEIRD subjects, participants in these studies are actually beyond WEIRD: they are almost exclusively right handed, and predominantly male.

7. Along this same line, the "lies" that are told in these studies rarely have an impact on the lives of the student participants. Occasionally, an extra reward is given if the participant is able to "trick" the system, but in the real world, with reputations and civil liberties at stake, one might imagine that one might do a better job at tricking the scanner. However, being instructed to lie about a low-stakes laboratory situation is not the same as the high-stress situations where this technology would be used in real-life. Occasionally, a study will try to ameliorate this situation by using a mock crime (such as a theft) as the deceptive stimuli. However, these are also of limited use as participants know that the situation is contrived.

6. Like traditional polygraph tests, it is possible to fool brain-based lie detection systems with countermeasures. Indeed, in an article in press at NeuroImage, Ganis and colleagues found that deliberate countermeasures on the part of their participants dropped deception detection from 100% to 30%. Most studies of fMRI lie detection have found more brain activation for lies than truth, suggesting that it is more difficult for participants to lie. However, is this still the case with well-rehearsed lies? What about subjects performing mental arithmetic during truth to fool the scanner?
    
5. A general lack of consistency in the findings in the academic literature. To date, there are ~25 published, peer-reviewed studies of deception and fMRI. Of these studies there are at least as many brain areas implicated in deception, including the anterior prefrontal area, ventromedial prefrontal area, dorsolateral prefrontal area, parahippocampal areas, anterior cingulate, left posterior cingulate, temporal and subcortical caudate, right precuneous, left cerebellum, insula, putamen, caudate, thalamus, and various regions of temporal cortex! Of course, we know better than to believe that there is some dedicated "lying region" of the brain, and given the diversity of deception tasks (everything from "lie about this playing card" to "lie about things you typically do during the day"), the diversity of regions is not surprising. However, the lack of replication is a cause for concern, particularly when we are applying science to issues of civil liberties.

4. An additional issue surrounds the fact that many of these studies are not properly balanced. In other words, participants are instructed to lie more or less often than they are instructed to tell the truth.

3. There is a large difference between group averages and finding deception within an individual. Knowing that on average, brain region X is significantly more active in a group of subjects during deception than during truth does not tell you than for subject 2 on trial 9 than deception was likely to occur due to the differences in activation. Of course, some studies are trying to study this level of analysis, but right now they are the majority.

2. Some things that we think that are not true are not necessarily lies. Most of us believe we are above-average drivers, and smarter and more attractive than most even when these beliefs are not true. Memories, even so-called "flash-bulb" memories are not fool proof.

1. Are all lies equivalent to the brain?  Are lies about knowledge of a crime the same in the brain as white lies such as "no, honey those pants don't make you look fat" or lies of omission or self-deceiving lies?

My picks for the top studies of 2010

Presented in no particular order, here are the ten studies of 2010 that I found the most interesting. Enjoy!

1. A Wandering Mind is an Unhappy Mind
I wrote about this study here. Authors used an iPhone app to obtain "what are you doing?", "what are you thinking about?" and "how happy are you right now?" data. It turns out that we are thinking about something other than what we are doing about half of the time, and these are the times we are least happy.

2. Electrical Enhancement of Mathematical Ability.
I wrote about it here. The authors used transcranial direct-current stimulation as participants were learning an novel digit vocabulary. The stimulation (if done in the proper direction) facilitated this type of learning.

3. Ego Depletion only Happens if you Believe it will Happen.
I wrote about it here. Ego depletion is the idea that self-control is like a muscle, and if you use too much of it, you need to rest it like a muscle. The authors show here that people who believed in ego depletion had depleted continuous self-control, whereas people who believed that self-control was not a limited resource did not. Critically, giving people one of the two beliefs also changed behavior in the predicted direction.

4. Habit Formation in the Real World.
Have you heard that it takes 28 days to form a new habit? This is a very common notion, but is it true? The authors found that it can take up to 60 days for people to report a new behavior feeling automatic.

5. Vollenweider's Review of Psychadelic Drugs
Everything you ever wanted to know about psychedelics, but were afraid to ask. Good review of neurobiology of these drugs and their potential therapeutic uses in depression, OCD, anxiety, etc.

6. Eye Position Predicts what Number you have in Mind
When asked to generate "random" numbers, people have a hard time being truly random. In this study, people were asked to generate random numbers while their eye movements were monitored. It was found that the number a person generated could be predicted from the position of the eyes: in particular, that eyes in the lower left part of the visual field predicted small numbers and eyes in the upper right predicted large numbers.

7. Willful Modulation of Brain Activity in Disorders of Consciousness
Until this paper, there had been limited reports of patients in minimally conscious states able to perform mental imagery tasks as measured with fMRI. However, we also know that diagnosis of these states is prone to errors. How common is it for minimally conscious patients to be able to follow mental directions? 54 patients were tested, and it was found that only 5 could perform the tasks.

8. Putting Brain Training to the Test
Making software to "train your brain" into being smarter, more attentive, and less forgetful is a lucrative industry, but there was little evidence for or against this kind of training leading to cognitive enhancement. This massive study used over 11,000 participants and found that although participants got better at the tasks in the games, no improvement was found in non-trained real-world tasks. Save your money, folks.

9. Outcome Reporting Among Drug Trials
All clinical trials need to be registered through the NIH at clinicaltrials.gov. This policy was designed to prevent Big Pharma from running near-infinite numbers of trials on a drug, then only reporting ones with positive results. This study examines differences between studies funded by industry, by government and by private organizations. Industry-funded trials had 85% positive results, while government-funded trials had 50% positive results. Humph.
 
10. Prediction of Individual Brain Maturity
 Human brains mature rather late and at different rates. The issue of brain maturity has been key to policy decisions about how to punish adolescent criminals and how to insure adolescent drivers. This study uses fMRI to show how mature an individual brain is. 

Killingsworth MA, & Gilbert DT (2010). A wandering mind is an unhappy mind. Science (New York, N.Y.), 330 (6006) PMID: 21071660

Cohen Kadosh R, Soskic S, Iuculano T, Kanai R, & Walsh V (2010). Modulating neuronal activity produces specific and long-lasting changes in numerical competence. Current biology : CB, 20 (22), 2016-20 PMID: 21055945

Job V, Dweck CS, & Walton GM (2010). Ego depletion--is it all in your head?: implicit theories about willpower affect self-regulation. Psychological science : a journal of the American Psychological Society / APS, 21 (11), 1686-93 PMID: 20876879

Vollenweider FX, & Kometer M (2010). The neurobiology of psychedelic drugs: implications for the treatment of mood disorders. Nature reviews. Neuroscience, 11 (9), 642-51 PMID: 20717121

Loetscher, T., Bockisch, C., Nicholls, M., & Brugger, P. (2010). Eye position predicts what number you have in mind Current Biology, 20 (6) DOI: 10.1016/j.cub.2010.01.015

Monti, M., Vanhaudenhuyse, A., Coleman, M., Boly, M., Pickard, J., Tshibanda, L., Owen, A., & Laureys, S. (2010). Willful Modulation of Brain Activity in Disorders of Consciousness New England Journal of Medicine, 362 (7), 579-589 DOI: 10.1056/NEJMoa0905370

Owen, A., Hampshire, A., Grahn, J., Stenton, R., Dajani, S., Burns, A., Howard, R., & Ballard, C. (2010). Putting brain training to the test Nature, 465 (7299), 775-778 DOI: 10.1038/nature09042

Bourgeois FT, Murthy S, & Mandl KD (2010). Outcome reporting among drug trials registered in ClinicalTrials.gov. Annals of internal medicine, 153 (3), 158-66 PMID: 20679560

Dosenbach NU, Nardos B, Cohen AL, Fair DA, Power JD, Church JA, Nelson SM, Wig GS, Vogel AC, Lessov-Schlaggar CN, Barnes KA, Dubis JW, Feczko E, Coalson RS, Pruett JR Jr, Barch DM, Petersen SE, & Schlaggar BL (2010). Prediction of individual brain maturity using fMRI. Science (New York, N.Y.), 329 (5997), 1358-61 PMID: 20829489