MRI and Brain Fingerprinting in Court: Legal & Scientific Review

Introduction: Lie Detection and the Rise of Brain Imaging

Throughout history, folk methods have been proposed for discerning whether an individual is telling the truth or lying. The most popular modern method of lie detection — the polygraph machine — was developed in the 1930s; however, the accuracy of the polygraph is widely disputed. A newer method called brain fingerprinting examines the brainwaves of a subject to determine whether specific brainwave patterns appear after the individual has been shown a visual stimulus associated with the crime under investigation. The specific brainwave response will not appear unless the individual has some memory of the crime stored in the brain. Both the polygraph and brain fingerprinting have significant limitations, particularly regarding admissibility as court evidence.

A more recent technique — Functional Magnetic Resonance Imaging (fMRI) during deception — offers a different approach. When this method is used, "telltale areas of the brain 'light up' when a subject is using his or her mind to lie, areas that remain dark when the subject is giving a truthful answer" (Bean, 2007). This paper researches the use of MRIs and fMRI in court cases, examining the social consequences of advances in neuroscience, the legal problems these technologies create, and the legal perspectives that have emerged in response.

Neuroscience and the No-Lie fMRI

Neuroscience is defined as the "science concerned with the development, structure, function, chemistry, pharmacology, and pathology of the human nervous system... directed at exploring the architecture and functions of the brain as well as the effects of stimuli on parts of the brain and cerebral performance" (Committee on Science and Law, 2005). There are three main areas of research in neuroscience:

1) Imaging of the brain and other neurodiagnostic techniques; 2) Exertion of influence on the brain; and 3) Design and construction of the brain (Committee on Science and Law, 2005).

Technological innovations have changed investigatory methods throughout the entire history of the criminal justice system. One new technology holds the potential to "revolutionize the investigatory landscape" — brain fingerprinting (BF) (Taylor, 2007). Brain fingerprinting is an examination "designed to determine if particular information is familiar to a test subject in a specific context (such as that of a crime)" (Taylor, 2007). It works by testing whether the individual is "familiar with a particular place, time, or action, and does so using brain monitoring technology that is nearly impossible to deceive" (Taylor, 2007). In practice, brain fingerprinting monitors brain wave impulses.

There are four phases of a criminal case in which brain fingerprinting may be used: 1) Investigation; 2) Interviewing; 3) Scientific testing; and 4) Adjudication (Taylor, 2007).

Illes and Racine (2005), in their work "Imaging or Imagining? A Neuroethics Challenge Informed by Genetics," explain that brain fingerprinting works because "when the brain recognizes significant information — such as crime scene details — it responds with a 'memory and encoding related multifaceted electroencephalographic response.'" Unlike polygraph testing, which measures physiological markers associated with fear of being caught, brain fingerprinting ostensibly measures brainwaves emitted when stored information is recognized. Related to this, "new applications of fMRI that bridge cognitive science and law also have the potential to change approaches to truth verification and lie detection" (Illes and Racine, 2005). When individuals answer truthfully, fMRI shows "increased activity in visual and motor cortex" (Illes and Racine, 2005).

Illes and Racine further caution that "the brain image represents unparalleled complexity — from the specialized medical equipment needed to acquire a scan, to the array of parameters used to elicit activations and the statistical thresholds set to draw out meaningful patterns, to the expertise required for the objective interpretation of the maps themselves." The absence of standards of practice in the laboratory — where "innovation and creativity still define the state-of-the-art in neuroimaging today" — and the medicolegal setting together create another layer of complexity for drawing conclusions about behavior, responsibility, and cognitive well-being, requiring "appropriately responsive ethical approaches" (Illes and Racine, 2005).

Garland and Glimcher (2006), in "Cognitive Neuroscience and the Law," state that "advances in neuroscience now allow us to use physiological techniques to measure and assess mental states under a growing set of circumstances. The implication of this growing ability has not been lost on the western legal community." They also reference the work of neuroscientist Richard Davidson, who concluded that "individuals with hypoactivation of certain regions of the prefrontal cortex may be deficient in the instantiation of goal-directed behavior and in the overriding of more automatic responses. In particular, a lateral right-sided region of the orbital frontal cortex appears particularly responsive to punishments in normal subjects" (Garland and Glimcher, 2006).

The MRI utilizes radio waves and a strong magnetic field to provide detailed images of an individual's internal tissues and organs. Functional Magnetic Resonance Imaging (fMRI) is a newer application of this existing technology. During an fMRI scan, the patient lies on a table with the head braced and is asked to perform a specific task during imaging. The area of the brain responsible for that task increases its activity, resulting in a signal change in the image. The fMRI monitors the movement of blood to determine which areas of the brain are activated by a specific task. The blood oxygen level-dependent (BOLD) fMRI measures brain activity linked with deception: "activated areas of the human brain show a localized increase in blood flow. Thus the oxygen content of venous blood increases during brain activation, resulting in increased MR signal intensity" (Bansal, Singh, Sreenivas, and Pandey, 2004).

Daniel Langleben conducted fMRI testing with 18 volunteers and found that "sections of the brain that exercise a significant role in attention, and which monitor and control errors — the anterior cingulate gyrus and parts of the prefrontal and premotor cortex — were more active in the volunteers when they were lying than when they were telling the truth" (Bansal et al., 2004). According to Langleben, since truthful responding appears to be the brain's default response, "lying would require increased brain activity in the regions involved in inhibition and control" (Bansal et al., 2004).

The work of Davachi, Mitchell, and Wagner (2003), "Multiple Routes to Memory: Distinct Medial Temporal Lobe Processes Build Item and Source Memories," notes that "a central function of memory is to permit an organism to distinguish between stimuli that have been previously encountered and those that are novel." Their event-related fMRI study examined the relationship between activation in distinct medial temporal lobe subregions during memory formation and the ability to later recognize items as previously encountered or to recollect specific contextual details about prior encounters.

The Washington Post reported that the Siemens Magnetom Trio at one major university — a 10-foot-tall, 14-ton fMRI machine — is considered "the most formidable lie detector ever built" (2006).

Brain Fingerprinting: Method, Evidence, and Criticism

Brain fingerprinting is the creation of Dr. Lawrence A. Farwell. It is a computer-based technology for identifying individuals who committed a crime by measuring brain wave responses to pictures or words related to that crime. The basis of the technology is that a guilty individual will have sequences of crime details stored in the brain, whereas an innocent person would not (Bansal et al., 2004).

In the brain fingerprinting test, sensors attached to a headband measure the individual's electrical brain wave responses. Three types of stimuli are used: 1) Targets; 2) Irrelevant stimuli; and 3) Probes. These are presented "in the form of words, pictures, or sounds" by a computer for a second or even a fraction of a second. A notable incoming stimulus produces a P-300, an electrical brain response that is part of a larger response called a MERMER — a memory and encoding related multifaceted electroencephalographic response.

Originally, event-related potentials (ERP) were used to study information processing in the brain. The ERP's limitation is that it eliminates complex patterns, causing meaningful signals to be lost as well. The multifaceted electroencephalographic response analysis (MERA) was developed to address this limitation. Farwell found that when this technique was incorporated, a MERMER was elicited whenever the individual being tested recognized an incoming stimulus.

While fMRI is still in early stages — and scientists recommend further research to establish a valid base for comparing and corroborating pattern prediction in truth-telling and deception — the legal arena has already made use of brain fingerprinting results as evidence. Brain fingerprinting achieved a legal victory in the case of Terry Harrington, who was acquitted because "brain fingerprinting patterns did not match with the crime scene evidence" (Bansal et al., 2004).

Dr. Farwell's research has investigated the scientific validity of brain fingerprinting. He states that the P300 electrical brain wave response is "widely known and accepted in the scientific community and there have been hundreds of studies conducted and articles published on it over the past thirty years" (Interview with Dr. Farwell, n.d.). Dr. Farwell claims an accuracy rate of 100% for brain fingerprinting, stating that in 200 total tests "there have been no false positives or false negatives in instances where a determination of 'information present' or 'information absent' was made" (Taylor, 2007).

Critics of brain fingerprinting raise several concerns, including: the mental capacity of individuals to retain information during a crime (e.g., intoxication, drug use, extreme stress); incomplete understanding of how memories form during crimes; the possibility that individuals could attempt to deceive the test; the potential for bias introduced by the test administrator's selection of specific stimuli; and questions relating to civil liberties.

In response, Dr. Farwell argues that the brain always records information whether the individual is aware of it or not. He cites a case in which the subject "was on alcohol and drugs, and in a highly emotionally charged state at the time of the murder" and results were still "excellent." On the issue of deception, since brain fingerprinting tests for the presence of specific information rather than for truthfulness per se, "BF cannot be 'beaten' or fooled by relaxed, well-prepared criminals" (Taylor, 2007). Furthermore, "because the BF test is objective and measures a brain response at the moment of recognition, it is equally effective when given to a normal mentally stable individual as it is when given to a sociopath, hardened criminal, or pathological liar" (Taylor, 2007). On civil liberties, Dr. Farwell argues that brain fingerprinting "serves the cause of human rights by giving an innocent individual the means to scientifically prove his or her innocence," calling it a "human rights violation to deny access to testing to anyone who is accused of a crime" (Taylor, 2007).