Brain Fingerprinting: Detection of Concealed Information

The record stored in the brains of the witness and perpetrator is often a much more comprehensive account of the crime than what can be pieced together from connecting a few specific features of the crime scene with a few specific features of the perpetrator. This record has not been accessible to scrutiny. The stored record has the advantage of often providing by far the most comprehensive account of the crime available. Witness testimony is a subjective report of the contents of memory. Memory is known to be limited and imperfect in a number of ways (see Eyewitness Memory Issues in Civil Litigation). It is approximate, sometimes distorted, selective, and subject to numerous influences. It is known to be affected by mental or physical illness, injury, passage of time, drugs, and many other factors. The two primary disadvantages of witness testimony are (i) human memory is imperfect and (ii) the witness may lie. Investigators have developed psychophysiological methods to attempt to detect deception (see Deception: Detection of; Deception Detection). The fundamental premise of the various techniques for detection of deception is that lying produces emotional stress and other psychological effects, which in turn produce physiological arousal and other changes. These can be measured through changes in perspiration, blood pressure, breathing, and so on. The commonly used control question test in conventional detection of deception employs direct, relevant questions regarding participation in the crime, such as “Did you shoot Mr. Jones?” Lykken [1, 2] originated a new technique for discovering more of the details of the record of the crime stored in the brain. It is known as the guilty knowledge test (GKT) or concealed information test [3–6]. The conventional GKT is an adjunct to interrogation and testimony (see Interrogation). It is a method not of directly detecting evidence of a crime stored in the brain but of determining the veracity of a subject who is testifying regarding the evidence and who may be seeking to conceal his connection with it. Methods for detection of deception or credibility assessment have met with limited success. They have been used primarily to guide investigations rather than to definitively establish the relevant facts.