Deception is a fascinating, yet unsettling, trait that pervades all cultures and societies, festering in the fissures of fragile human relations. Lies can take various forms, whether it is the blatant manipulation of facts or subtle omissions; in either form, deception is the concerted suppression of the truth. The search for the truth-or the lack thereof- is something social scientists have pursued for centuries, in an effort to relieve the distrust and deceit that destabilize social relations. However, it is difficult to identify a liar with consistency and certainty. What behavioral markers does one look for? Shifty eyes, a shaky voice, and trembling hands are not sufficient evidence in the context of a courtroom prosecution. It is true that the anxiety of deceit is channeled in these peripheral physical actions, but it was necessary for those interested in detecting deception to approach the highly subjective issue of deception in a more objective fashion. Consequently, these efforts turned to the purely objective approach - ‘expert’ science. Thus the following seminal questions were posed- is there science behind lying? Are there certain biological processes directly involved in deception? More importantly, is there a way to detect these physiological parameters? Numerous scientists and technologies have been utilized by social scientists and lawmakers to answer these questions.
The world’s first “physiological” lie detector was the polygraph. The machine was the mainstay of forensic lie detection for almost a century before scientists began looking at the true purported source of lying- the brain. The introduction of electroencephalography (EEG) provided great insight into the potential advantages of using neurophysiologic measures to observe the process of deception in the brain. The latest “neurotechnology” that has hit the lie detection scene is fMRI. Scientists claim that fMRI- or functional magnetic resonance imaging- can detect increased blood flow to key areas of the brain that are supposedly implicated in the “thought process of lying”. This forces the quandary- how far can one equate neurobiology and emotional thought processes involved in deceptive behavior?
fMRI-The cartographer of cognition?
Functional magnetic resonance imaging – or fMRI - enables researchers to create maps of the brain in action as it process thoughts, sensations, memories, and motor commands. Since its introduction to experimental medicine ten years ago, fMRI has been successfully used in the prognosis of diseases like Alzheimer’s and schizophrenia, and the evaluation of drug treatments. fMRIs have also been used in conjunction with neurosurgery to localize damage.5 More recently, researchers have claimed that fMRIs have given insight into the cognitive operations behind such complex and subtle behavior such as deception.
Daniel Langleben, a psychiatrist at the University of Pennsylvania, was one of the first scientists to research the technology’s applications in deception. His foray into the area was, however, inadvertent. “When I was studying adolescent boys with ADHD, I was intrigued by the observation that these children had difficulty lying. Children with ADHD have impulse control problems, they cannot inhibit their reactions. As a result, the truth that is sitting there in their brains, just bubbles out”. From this starting point, Dr. Langleben began to study whether there was a biological difference between ‘truth’ and ‘lie’, using fMRI. So, how exactly does fMRI project an ‘accurate’ representation of a ‘truth’ and a ‘lie’?
In an interview, James Loughead, professor of neuropsychology at Penn and one of Langleben’s collaborators, elucidated how brain fMRI is performed by placing the head or the entire body in the bore of an MRI scanner, built around a powerful electrical magnet (whose magnetic field is around 105 times stronger than the Earth’s). The polarized magnetic field causes the hydrogen nuclei in water in the body to resonate and emit radiofrequency signals that are eventually reconstructed into a three-dimensional image that reflects the relative concentrations of the hydrogen nuclei in the tissues.
“The key quantification that an fMRI gives us is the haemodynamic response- or the Blood Oxygen Dependent Level (BOLD),” Dr. Loughead explained. “When local oxygen demand rises in response to increased electrical activity and metabolism, the BOLD signal changes. The BOLD signal can therefore tell us in which areas of the brain neurons are most active in response to various experiences”.
“Lying is an involuntary action; it’s not something you can suppress,” Loughead explained. “You need to exercise a system that is in charge of regulating and controlling your behavior when you lie more than when you say the truth”. Langleben and Loughead used the Guilty Knowledge Test (GKT) in which subjects were given envelopes with a playing card in it, and they were asked to lie about the identity of the card. Once in the scanner, the subjects were shown a series of pictures of playing cards, including the one they had in their pocket, and they pressed ‘yes’ or ‘no’ to each card. When it came to the card they were hiding, they would say ‘no’- and this would constitute a lie.
“The basis of the test is a robust human response to salience”, says David Seelig, a graduate student in Langleben’s lab. “If you were to present suspects with various murder weapons, including the one found at the crime scene, the reaction to salience is something that can be detected by the fMRI, and researchers can see which suspects show an increased brain response to the real weapon”.
According to the studies conducted by Langleben and Loughead, the parts of the brain that are most active during deception are the inferior frontal gyrus and the inferior parietal lobe (together they make up the prefrontal parietal network important in detecting salience) and bilateral frontal cortex. The increased blood flow to these areas, as represented by the BOLD patterns, indicated that these areas were working harder in telling a ‘lie’ than they were in telling the ‘truth’. Langleben and Loughead have provided the desired cognitive markers that neuroscientists, psychologists, lawmakers and the general public have been looking for ever since the downfall of the polygraph. Their data also, however, raises some important questions- is deception in such an instructive manner (that is, the subject is essentially instructed to lie) really deception? As Seelig explains, the fMRI does not measure two important components of lying- the emotional response and the intention of the ‘liar’ to instill false belief in another person. “Telling a story is very different from simply responding to ‘Yes’ or ‘No’ questions; you have to maintain two realities. This requires the emotional component of deception, controlled by the limbic network.” The limbic network includes the purported emotional center of the brain- the amygdala. These aspects, in addition to the cognitive component, give a more accurate representation of deception. Considering this, what are the implications of using an fMRI in legal and security milieu? If it is not a true representation, there is the risk of falsely incriminating someone, either in a situation as dire as court or as routine as job screenings.
What is the future of the fMRI lie detector?
To date, all fMRI lie detection studies have utilized small sample sizes with individuals who were asked to lie about very concrete facts such as the type of card they were holding. This is by no means a simulation of reality—one must account for different factors such as age, mental state, and, as Seelig pointed out, how good a liar one is. Pathological liars do exist, and these people may be so adept at suppressing the truth- our emotional baseline as postulated by Langleben- that they may never be caught. Whatever the degree of deception, the anxiety a suspect will face in a real-life detection situation is entirely absent from a lab setting. Furthermore, the fMRI does not account for substance abuse (prevalent amongst criminals), which can greatly alter BOLD levels. Given all these constraints, in order for the fMRI to have any credibility in a court, a consensus of scientists agreed that more testing is necessary, with larger subject groups and in ecologically valid circumstances in order to isolate these neurological markers of deception on a single-subject basis.
Where does this leave us in our search for the science behind lying? The need for transparency has intensified as we as a human race struggle to find security in the fragile and unpredictable economic, social and political constructions. An integral part of finding security is co-opting an identity that is morally and culturally acceptable. Some believe that an individual integrates both social and biological circumstances in constructing this identity. This co-opting of identities and categories is both bottom up (by a single individual) and top down (by a governing body). Detecting deception exemplifies this top down categorization, where designated figures of society- governments, lawmakers, security agencies, and corporations- are put in place to maintain the dynamics and identities of the consisting population. The fMRI lie detector may facilitate this process, but only to a certain extent. The scientists and the aforementioned social authorities must pose the question of how transparent the mind really is. Are we looking to create biological categories of “liars” and “truth tellers”? Moreover, is it ethically acceptable to create these types of stringent categories? The answers to these questions will determine the trajectory of the fMRI in lie detection, and more importantly, whether we will ever find a scientific explanation to an elusive human behavior that enmeshes us in a web of secrets, facts, forgotten memories and fantasy: Deception.
