According to the theory of brain fingerprinting,
the brain produces an electrical surge 300 milliseconds after being presented
with information it recognizes as “significant.” The surge,
called a P300 wave, is followed slightly later by a dip in voltage. Farwell
found the man did not produce P300 waves when confronted with details
about the crime scene but did produce the waves when elements relevant
to his alibi flashed across the computer screen. Farwell concluded the
man’s brain did not contain information about the crime.
Although brain fingerprinting was accepted as evidence,
the judge in the case was highly skeptical. In a later proceeding, the
Iowa Supreme Court released the man because of a due-process violation
at the time of his original trial but made no mention of Farwell’s
science.
Farwell says his technology, which he claims to have
tested on 200 subjects, has “not yet yielded an incorrect answer”—no
false positives, no false negatives and only about 3% indeterminate responses.
His studies include one at Federal Bureau of Investigation headquarters
in Quantico, Va., in which Farwell says he correctly identified 17 FBI
agents and four non-agents based on P300 responses to the name of the
form the FBI uses to reimburse travel expenses. Still, critics contend
brain fingerprinting has never been adequately evaluated in the scientific
literature. During the past decade, Farwell has published a single relevant
peer-reviewed study, based on experiments involving just six subjects.
Each of these technologies attempts to unlock brain-bound
mysteries, raising many questions, says Paul Root Wolpe, a bioethicist
at the University of Pennsylvania. Some involve the science itself, others
relate to legal admissibility or ethical dilemmas. “How far does
the right to privacy extend?” Wolpe asks. “Could a court compel
a scan, as it can require DNA testing? Or is the skull inviolate?”
Spence, the fMRI pioneer at the University of Sheffield,
worries about rushing the new technologies to market. He is especially
concerned that laboratory studies have so far involved only subjects with
little at stake. “Lying isn’t terribly distressing for them,” Spence
says. “It would be very different for people who are suspects.”
Wolpe is particularly disturbed by Kozel and George’s interest in
the approach that would shut down a person’s ability to deceive. “We
don’t even know whether the areas of the brain activated during
deception cause the deception, are the mind reflecting on the lie, are
an emotional reaction or what,” he says. “This is an utter
shot in the dark.”
On the legal front, two principal tests govern admissibility
of scientific evidence. The Frye standard, which
dates to 1923 and tends to hold sway in state courts, asks whether a test
is generally accepted in science. During the 1990s, the federal courts
replaced Frye with the more specific Daubert standard, which considers
whether a technology has been peer-reviewed and whether its specificity
and sensitivity are known. Yet both standards serve only as guidelines:
The judge in a case decides what to admit based on the testimony of expert
witnesses.
“That really bothers me,” says Hank Greely, a professor at Stanford
University Law School. “You might have a good judge and bad experts, or
the judge could reach the wrong conclusion.” Greely wants regulatory oversight
of new lie detection technologies, perhaps by the Food and Drug Administration,
whose drug approval protocol is “the closest thing we have to a data-driven
process on safety and efficacy,” he says.
Other questions concern how new technologies might be used in the “war
on terror.” Currently, none would be feasible for an uncooperative detainee.
But what if it became permissible to force a prisoner into being scanned?
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