Brain fingerprinting

This term has received publicity recently through its use as a plot device in Peter May’s thriller Chinese Whispers, published earlier this year. However, the technique is a real one that has been investigated by the FBI in the hope that it will prove a more accurate alternative to lie-detector (polygraph) tests. The system is said to exploit a signal in the brain that responds to a stimulus with special significance to the individual concerned — such as the memory of a place or a person’s face. While monitoring the signal using scalp electrodes, the suspect is shown photographs of a weapon, a person or a crime scene. The electrical signal is said to respond positively if the suspect has guilty knowledge, even if no questions are asked and he stays silent. Sceptics point out that memories change over time and that as yet there’s no evidence that all people respond similarly in such situations, nor whether good self-control or psychological denial might prevent the signals appearing.

The CCLE [Center for Cognitive Liberty and Ethics, California] has no problem with brain fingerprinting so long as it’s voluntary ... Our concern is that law enforcement agents will seek to use it coercively. Such compelled use ought to be forbidden, because it would pierce one of the most private and intimate human spheres: our own memory.

New Scientist, 24 Apr. 2004

Unlike discredited lie-detecting techniques, which measure changes in breathing, heart rate and other variables to determine if suspects are trying to deceive their interrogators, brain fingerprinting is designed to discover if specific information is stored in a person’s brain.

Observer, 25 Apr. 2004