Neuroimaging Techniques for Memory Detection: Scientific, Ethical, and Legal Issues

Abstract

There is considerable interest in the use of neuroimaging techniques for forensic purposes. Memory detection techniques, including the well-publicized Brain Fingerprinting technique (Brain Fingerprinting Laboratories, Inc., Seattle WA), exploit the fact that the brain responds differently to sensory stimuli to which it has been exposed before. When a stimulus is specifically associated with a crime, the resulting brain activity should differentiate between someone who was present at the crime and someone who was not. This article reviews the scientific literature on three such techniques: priming, old/new, and P300 effects. The forensic potential of these techniques is evaluated based on four criteria: specificity, automaticity, encoding flexibility, and longevity. This article concludes that none of the techniques are devoid of forensic potential, although much research is yet to be done. Ethical issues, including rights to privacy and against self-incrimination, are discussed. A discussion of legal issues concludes that current memory detection techniques do not yet meet United States standards of legal admissibility.

Keywords:

• neuroethics
• neuroimaging
• memory
• Brain Fingerprinting
• lie detection
• Daubert

Notes

¹Memory dampening techniques, which are pharmaceutical in nature (Brunet et al. 2007; Doyère et al. 2007; Pitman et al. 2002), are different than erasure techniques in that they are designed to reduce the emotional intensity of memories (e.g., for the treatment of post-traumatic stress disorder). Such techniques are not hindered by the distribution and network characteristics of memory storage because the emotional component of memories is handled by localized processes that specifically act on those memories that are currently active (i.e., new or reactivated).

2. Two hypotheses stated here are not without controversy among memory scientists. Namely that: 1) familiarity and recollection are supported by distinct retrieval processes, and 2) the mid-frontal and parietal old/new effects represent familiarity and recollection, respectively. Nevertheless, the application to memory detection is unaffected by these scientific controversies. In other words, as long as an old/new effect distinguishes old from new events, it does not matter whether that effect is uniquely associated with a particular mnemonic process or experience.

3. The Brain Fingerprinting test is a P300 memory detection test originally developed by Farwell and Donchin (1991) and more recently commercialized by Brain Fingerprinting Laboratories, Inc., Seattle, WA (Rosenfeld 2005). The PBS special was part of the Innovation series, and originally aired in May 2004; available at: http://www.pbs.org/wnet/innovation/episode8.html (accessed December 7, 2007).

4. The attenuation of the P300 under high mental effort conditions suggests another possible countermeasure strategy in which the guilty examinee increases task difficulty by covertly performing a second task during the memory detection test (Bashore and Rapp 1993). One limitation of this strategy is that the constant performance of the second task should affect the P300 for all stimuli (i.e., not just probes), and thus the probe P300 should still look target-like.

5. The scientific problems associated with the potentials, other than the P300 potential, used in the Brain Fingerprinting test were reviewed by Rosenfeld (2005). Moenssens (2002), like the Iowa District Court judge, is under the mistaken assumption that the only science yet to be conducted before the Brain Fingerprinting test meets the Daubert standard relates to the these other potentials. I, on the other hand, submit that the use of P300 memory detection does not yet meet the Daubert standard.