To understand why “lie detection” is controversial, we need to get into the history of it a little bit, and we also need to explain what different ideas are floating around. We'll make it quick.
History of "Lie Detection"
There has never been a fool-proof method to show whether someone is telling the truth or lying. Historically, we “solved” this problem with torture. From antiquity through the Middle Ages, trial by ordeal was used as if surviving water or fire proved innocence.1)
In the 20th century, American scientists tried to develop ways of measuring physiology during questioning that could prove truthfulness or deception. Special devices (dubbed “polygraphs”) were built to measure breathing and heart rates as well as sweating.2) But the courts were quick to reject these new methods for their lack of acceptance in relevant scientific communities. Instead it was decided that first scientists had to agree a certain method of gathering evidence was actually scientific for courts to accept it as evidence.3) Three generations of refuted claims4) later, the state of “lie detection” is still that we're asked to believe experts who often have a huge financial stake in the technology.
That hasn't stopped a 3-4 billion dollar industry5) from developing in the US. “Officially licensed polygraphers” make people pay money for polygraph tests that they can try to use in courts or other proceedings (naturally only if they like the results) and the US intelligence and security apparatus makes extensive (and controversial) use of lie detection to try and find moles, leakers, terrorists, and other criminals.6)
“Lie detection” never did achieve that broad legal or scientific acceptance, because no lie response was ever discovered that uniquely identifies when people are being deceptive or truthful. Rather, most psychophysiologists and psychologists think lie detection is not theoretically sound.7) They doubt the high accuracy claims that are floating around are supported by evidence, and they believe polygraphs can be easily beaten with countermeasures8).
In the early 2000s, Congress asked leading scientists at the National Academy of Sciences to evaluate the scientific evidence behind polygraphs.9) The scientists issued a report warning that using polygraphs for mass security screenings would harm national security by wrongly implicating large numbers of innocent people as deceptive while also failing to identify a non-negligible proportion of guilty people.10) And because most of the available research on lie detection was of such poor quality, they refused to publish an average accuracy rate or range at all11).
"Lie Detection" in Europe
The American polygraph industry currently dominates globally, but in Europe lie detection has traditionally been associated with the Soviets.12) The Stasi in East Germany also used Soviet polygraph interrogation techniques as part of its intimidation and “touchless torture” repertoire.13) Police in Eastern European countries such as Poland, Romania, Slovenia, Latvia and Lithuania commonly use polygraphs in police investigations and personnel security screenings.14)
"Next generation lie detection"
In recent years, new techniques for lie detection have been proposed. Instead of measuring the crude physiological parameters of the old polygraphs, relatively new approaches generally suggest measuring pupil dilation, small eye and facial movements, facial thermography, signs of stress in the voice, posture, and linguistic analysis. The current holy grail appears to be the use of machine learning to study the data from ever-cheaper EEG headsets, directly measuring the electrical activity in the brain itself—when questions can be structured in terms of concealed information rather than deception per se.15) Scholars are increasingly concerned about emerging and possible abuses of these EEG-based brain measurements.16)
Border security is the main growth area for lie detection in Europe. The European security market is growing and set to be worth 128 billion euros by 2020.17). In October 2018, the European Commission announced that as part of the €80 billion Horizon 2020 EU Research and Innovation initiative, it was funding iBorderCtrl (the Intelligent Portable Border Control System) to the tune of €4.5 million. iBorderCtrl includes a lie detection component called ADDS (Automatic Deception Detection System) from a company called “Silent Talker”, a startup staffed by scientists from the Manchester Metropolitan University.
In the case of iBorderCtrl, the self-reported accuracy numbers sound good. However, even if we were to believe them, they are still problematic in a mass-screening context.18) But for now nontransparency in both science and ethics surrounding the project prevent us from saying for sure whether this current next-generation lie detection is any more scientifically sound that the previous generations. If it isn't, then Europe is rolling out pseudoscientific technology to intimidate travelers.19) If it is, then it raises a host of other issues.20)
Introduction of iBorderCtrl in its proposed form would be the largest rollout of “lie detection” in the world, and it would mark the first time (we know of) that parts of the general population would be subjected to lie detection en masse.
As far as we know, the studies done on the Automatic Deception Detection System have been done by insiders, who stand to become very rich if their system is adopted along the European borders. The progress reporting to the EU is all confidential. This system needs to be studied out in the open, by independent scientists.
We need some informed debate on lie detection and its potential uses and abuses.
This technology is far too controversial to be put into general use by mid-level bureaucrats without proper oversight.
… while the courts will go a long way in admitting experimental testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.The so-called Frye standard of general acceptance kept polygraph “test” results out. It also governed scientific evidence admissibility in the US for most of the 20th century, and still governs in several states. Elsewhere it has been combined with or superseded by the 1993 Daubert and hybrid Frye-Daubert standards. Polygraph “tests” generally remain inadmissible in criminal courts due to concerns about poor quality methodology in existing studies of polygraph validity, and unpredictable accuracy. But roughly half of US states currently admit stipulated polygraph tests as evidence, New Mexico admits them per se, and polygraph proponents often try to argue the evidence for admissibility under the Frye and Daubert standards. However, in another landmark case, the Supreme Court later ruled in US v. Scheffer, 523 U.S. 303 (1998) that scientific concerns about polygraphs' accuracy, reliability, and susceptibility to countermeasures had rightly prevented an airman from presenting polygraph “evidence” in his defense in court-martial proceedings. In 2005, the heads of a National Academy of Sciences committee to review the scientific evidence on the polygraph wrote in their peer-reviewed summary of that work:
We believe that the courts have been justified in casting a skeptical eye on the relevance and suitability of polygraph test results as legal evidence. Generalizing from the available scientific evidence to the circumstances of a particular polygraph examination is fraught with difficulty. Further, the courts should extend their reluctance to rely upon the polygraph to the many quasiforensic uses that are emerging, such as in sex offender management programs (see the discussion in ). The courts and the legal system should not act as if there is a scientific basis for many, if any, of these uses. They need to hear the truth about lie detection.
As this paper was going to press in January 2005, the Department of Energy finally announced its proposed revised polygraph rules in the Federal Register .They provide a detailed plan for implementing the plan outlined in Deputy Secretary McSlarrow’s September 2003 testimony. But no other federal agency has stepped forward with a plan to curb the use of polygraphs. All of them have heard the truth about polygraphs as we know it, but they have failed to acknowledge it by action.Ultimately, in 2006, the DOE did issue a regulation limiting polygraphs of its employees to certain cases with specific cause, as opposed to the mass screening program they (repeatedly) tried to implement following the Wen Ho Lee scandal.
determined that the polygraph was not a worthless tool – indeed, that it was much worse than worthless. The report said that “available evidence indicates that polygraph testing as currently used has extremely serious limitations . . . if the intent is both to identify security risks and protect valued employees.” The NAS panel, made up of internationally respected psychologists and statisticians, further determined that the test was so nonspecific that even if the polygraphers managed to finally uncover their first spy, at least 100 innocent laboratory employees would have their clearances yanked because of the “false positives” inherent in the test. The NAS concluded: “Polygraph testing yields an unacceptable choice . . . between too many loyal employees falsely judged deceptive and too many major security threats left undetected. Its accuracy . . . is insufficient to justify reliance on its use in employee security screening in federal agencies.” It doesn't get much clearer than that.Despite having cleared this op-ed before publication, Zelicoff was subsequently forced to resign in retaliation for his opposition to polygraphs.
OTA recognizes that the administration as well as NSA, CIA, and DOD believe that the polygraphis a useful screening tool. However, OTA concluded that the available research evidence does not establish the scientific validity of the polygraph for this purpose.
there is a large and consistently expanding global network of U.S. polygraph training and equipment recipients in the form of other governments… polygraph programs are required as part of U.S. sponsored anti-corruption programs such as Plan Colombia, the Mérida Initiative in Mexico, and others in the Bahamas, Bolivia, Guatemala, Honduras, and Iraq (U.S. Government Accountability Office 2010; U.S. Department of State 2010).
attractive on grounds of basic psychophysiology because of the possibility that appropriately selected brain measures might get closer than any autonomic measures to psychological processes that are closely tied to deception. Brain activity can be measured with modern functional imaging techniques such as positron emission tomography (PET) and magnetic resonance imaging (MRI, often referred to as functional MRI or fMRI when used to relate brain function to behavior), as well as by recording event-related potentials, characteristics of brain electrical activity following specific discrete stimuli or “events”…(p. 154-5). The scientists went on to identify several problems with fMRI for deception detection (p. 159-160).
Various techniques for detecting deception have been suggested or might be used as substitutes for or supplements to the polygraph. None of them has received as much research attention as the polygraph in the context of detecting deception, so evidence on accuracy is only minimal for most of the techniques. Some of the potential alternatives show promise, but none has yet been shown to outperform the polygraph. None shows any promise of supplanting the polygraph for screening purposes in the near term. Our conclusions are based on basic scientific knowledge and available information about accuracy.