Brain fingerprinting: Encyclopedia - Brain fingerprinting

Brain fingerprinting

Brain fingerprinting is a technique that measures recognition of familiar stimuli by measuring electrical brain wave responses to words, phrases, or pictures that are presented on a computer screen. Brain fingerprinting was invented by Dr. Lawrence Farwell. The theory is that the suspect's reaction to the details of an event or activity will reflect if the suspect had prior knowledge of the event or activity. This test uses the Memory and Encoding Related Multifaceted Electroencephalographic Response to detect familiarity reaction. It is hoped it might be more accurate than a polygraph (lie-detector) test, which measures physiological signals such as heart rate, sweating, and blood pressure.

The person to be tested wears a special headband with electronic sensors that measure the EEG from several locations on the scalp. In order to calibrate the brain fingerprinting system, the testee is first presented with a series of irrelevant stimuli, words, and pictures, and then a series of relevant stimuli, words, and pictures. The testee’s brain response to these two different types of stimuli allow the testor to determine if the measured brain responses to test stimuli, called probes, are more similar to the relevant or irrelevant responses.

The technique uses the fact that an electrical signal known as P300 is emitted from an individuals brain exactly 300 milliseconds after it is confronted with a stimulus that has special significance to that individual (e.g. a murder weapon or a victim's face). Because it is based on EEG signals, the system does not require the testee to issue verbal responses to questions or stimuli. Also, unlike polygraph testing, it does not attempt to determine whether or not the testee is lying or telling the truth. Rather, it attempts to measure the testee’s brain response to a record of relevant words, phrases, or pictures.

Brain fingerprinting - Background and terminology

"Brain fingerprinting" is a portable test that is advertised to be able to discover, document, and provide evidence of guilt, affectedness by marketing, and identify members of dormant terrorist cells. This is primarily a discussion of the Dr. Lawrence Farwell's paper, “Using Brain MERMER Testing to Detect Concealed Knowledge Despite Efforts to Conceal” [1], published in the Journal of Forensic Sciences in 2001 by Dr. Farwell and FBI Special Agent Ms. Smith of the FBI. This paper describes a test of brain fingerprinting, a technology based on EEG that is purported to be able to detect the existence of prior knowledge or memory in the brain. The P300 occurs when the tested subject is presented with a stimulus that they feel is significant. When an irrelevant stimulus is presented, a P300 is not expected to occur. The P300 is widely known in the scientific community, and is also known as an Oddball-evoked P300. A similar response occurs in as a P600 or N400 during syntactic or semantic processing and is elicited by inappropriate words or strange grammar structures. The main goal of Farwell's brain fingerprinting tests upon deceptive subjects is to prove that the perceptions and goals of the subject upon their non-cognitive brain processes has zero effect upon the efficacy of the MERMER test.

While researching the P300, the author of this paper, Dr. Farwell, created a more detailed test that not only included the P300, but also observes the stimulus response up to 800ms after the stimulus. He calls this technique a MERMER, memory and encoding related multifaceted electroencephalographic response. This P300, an electrically positive component, maximal at the midline parietal area of the head, has a peak latency of approximately 300 to 800 ms. The MERMER s an electrically negative component, maximal at the midline frontal area, with an onset latency of approximately 800-1200ms.

Brain fingerprinting - Justification

The stated purpose of this technology is to test the possibility of using the brain as a source of information that could potentially reveal an uncooperative suspect’s presence at the scene of a crime. Brain fingerprinting utilises the addition of three advances upon a previous methodology using EEGs. Brain MERMER testing purports to offer 100% accuracy of results, with no false positives, no false negatives, and no indeterminate results.

Dr. Farwell's latest publications detail his attempts to discover and report upon the relationship between a MERMER and the proof or absence of the tested for information within the subject’s brain. This technology use a idiographic model of explanation which attempts to prove with 100% accuracy that a positive MERMER result correlates with the tested for information present in the brain. The unit of analysis for this study is an induced neurological artifact in a specific subject, of whom the tester has prior knowledge. The tester produces an image, sound, or written word to the subject, and measures the neurological reaction using the author’s MERMER test.

Dr. Farwall has stated that criminal investigators are in need of an accurate, scientific method of linking a criminal to a crime. MERMER technology is compared to fingerprinting and DNA testing in importance and states that MERMER testing will render all other forms of criminal investigation to be secondary in terms of ease of data collection and preservation. He has also stated that unlike DNA and fingerprinting, MERMER could be used to link one piece of evidence to an unlimited number of individuals. Unlike blood or a print, the possession of information by more than one individual is possible. Dr. Farwell states that through this infallible method, the innocent can prove their innocence with a minimum of stress or invasive testing.

While the justification for brain fingerprinting is well defined in terms of subordinate problems, the stated problems are very general and applicable to any statement about criminal prosecution. There is a great absence of mention of comparable technologies, such as the polygraph. The study itself is very limited — it seeks to ascertain and confirm that MERMER signatures will identify if a subject has a specific memory or not. The authors make a very concerted effort to orient the reader and to show the relevancy of the study by discussing related literature. However, exactly half of the works cited are by the author, and many of those are unpublished reports for government or institution use. This may cast doubt on the actual importance and importance that is placed on this problem in the field.

The sources of data and the method are well detailed, yet still leave the reader unable to replicate the results. The study used six test subjects; however, the method of selection, and any discussion relating to prescreen procedures was noticeably absent. The removal of one test subject’s data was due to a misunderstanding of the test instructions. Although, a reader of the study might refer to the title of the study, and question if a subject with intent to conceal knowledge is similar to someone that does not understand the test at all. The explained need for the study is an old and deep societal need to identify the innocent from the guilty.

Brain fingerprinting - Criticisms

Some believe brain fingerprinting needs far more refinement before its use becomes widespread and court cases are decided on its evidence. A large proportion of the scientific community believes that this new test will have the same limitations as the older polygraph test. Several studies have shown it is possible to control electroencephalographic response in much the same way as it is possible to fool a polygraph test; however, a higher level of training and discipline is required.

Neither American or European courts admit "brain fingerprints" as evidence.

MERMER is inappropriate for use in crimes that do not rely upon information being present while the crime was committed, since both people have equal knowledge of the crime. Farwell also acknowledges that where there is no information that law enforcement officials possess that the criminal does not also possess, the test is not appropriate.

The MERMER system exploits the known Oddball-evoked P300, which is similar in function to the N400 and P600 that have been documented by Kutas and Hillyard of Sandiego, and Osterhout and Holcomb. These two ERPs are used to measure brain wave response to unexpected or “oddball” anomalous words or grammar formations, but the N400 and P600 waves are measured in the same locations and using very similar methodology to the MERMER system. In the comparative analysis, there is evidence that this controlled system of 99.9% accuracy in detecting “information present” have been refuted, rendering the MERMER system to be irrelevant. The P300 has been shown to be related to “information present” analysis, in addition to a multitude of unknown factors. Farwell’s documented analysis of 99.9% accuracy with no false positives is entirely based on a well-chosen set of participants and artfully designed questioning, not on the accuracy of the system in real-world scenario with unknown suspects.

Brain fingerprinting - Ethical considerations

Farwell ignores the ethical considerations of the ability to interpret someone’s mind to test if they possess specific knowledge. The designers and supporters of brain fingerprinting do not seem concerned with the unethical uses of this technology, and have made it clear that this test is designed for, and created with the aid of, government agencies. Some feel that a discussion of the humanitarian use in reducing stress for innocent people that are accused is unethical when the ethics of the technology itself is not discussed.

Brain fingerprinting - Conflicting evidence

Johnson and Rosenfeld of Northwestern University have published two papers that refute the MERMER system’s accuracy. The first test was a recreation of P300 guilty-knowledge testing similar to a simplified MERMER, however, it did not require a rehearsal of the Target and Probe stimulus. Subjects were required to complete a checklist in advance of their crimes in terms of “innocent/not innocent,” which implies that this test has not yet been applied by a tester that does not possess foreknowledge of the subject’s understanding or perception of his own crime. They were able to correctly classify 89% of the subjects.

In another paper by Johnson and Rosenfeld, they developed specific countermeasures to generate a false positive to the p300 test as proposed by Donchin and Farwell in their collaborative paper that initially proposed the connection between the P300 and lie detection. Johnson and Rosenfeld beat Farwell and Donchin’s proposed lie detector test by imagining an emotional event at the same time as the target and probe stimulus was presented. The subjects trained in countermeasures were able to defeat the P300 lie detector test’s attempts to classify them by 90% after 5 practice trials. They were completely unable to produce false positives.

This would imply that the MESMER test, which is an expansion of the P300 Oddball-Evoked Guilty Knowledge Test, is also under attack, as there is no chance of a 100% correct guilty or “information present” classification. These two papers imply that a MESMER test cannot correctly identify a subject with knowledge of a crime, and definitely not within 99.9%. The Farwell MERMER system is in serious jeopardy in light of the recent publications by Johnson and Rosenfeld, and therefore, cannot be given any credence until further tests in favour of the MERMER system are administered using the techniques carried out by Rosenfeld and Johnson.

Currently, there has been only one field study published that has used a P300 Guilty Knowledge Test to verify its accuracy, but this group reported chance accuracy, definitely inconsistent with Farwell’s reported 100% accuracy. It has also been shown in Rosenfeld and Johnson’s countermeasures paper that while defeating the MERMER system is possible, it will necessarily require practice and an educated guess about the nature of the probes that will be presented. It is noted that common affective murderers and similar criminals may not have access to psychophysiology experts, it is conceivable that foreign terrorists will have such access and ability, rendering the MERMER system useful only against the uninitiated. After receiving countermeasure training, Johnson and Rosenfeld reported a change from 82% correctly classified “guilty” subjects to 18% after countermeasure training.

Brain fingerprinting - Current uses and research

It has been tentatively used by the FBI to test for recognition of crime scenes in hope of proving guilt. It is not admissible in court.

Dr. Farwell also proposes the use of this test for airport screening and other forms of routine employment, military, and foreign intelligence screening. However, clearly, one cannot make such proposals based on such small sample sizes with such rigorously controlled stimulus and response mechanisms in a contrived environment.

Jimmy Ray Slaughter was convicted in 1991 of the murder of his former girlfriend and their eleven month old daughter. In February 2004, Dr. Farwell ran the brain fingerprinting on Jimmy Ray and showed he had never seen the crime scene. "Jimmy Ray Slaughter did not know where in the house the murder took place; he didn't know where the mother's body was lying or what was on her clothing at the time of death — a salient fact in the case," says Dr Farwell. Jimmy Ray Slaughter was executed by the state of Oklahoma on March 15, 2005.

Research into brain fingerprinting is currently being funded by the CIA. Its use has been touted as a means of intelligence gathering to prevent terrorism.

Farwell’s MERMER system is not, and has been proven to have any more accuracy than chance, and is only valid under extremely controlled and contrived circumstances. While new forms of lie detection are currently under development, these are generally based on fMRI, PET, and are based on events in the prefrontal cortex. Currently fMRI evidence of ability to perform moral reasoning before the age of 18 is being considered as evidence in a case by the United States Supreme Court. Farwell’s MERMER has been accepted as evidence in the Iowa Supreme Court on two occasions. It is critical for scientists to continue to pursue examinations of these discovered and applied technologies, particularly as their application has begun to have a very real and serious impact upon the freedom of citizens.

Adapted from the Wikipedia article "Brain fingerprinting", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki