A new "truth-telling" industry is emerging in the US which uses brain scans to determine whether or not people are lying. But experts are already questioning the ethics and validity of such tests.

The trouble began in 2003 when a fire gutted Harvey Nathan’s deli in Charleston, South Carolina. In the aftermath, Nathan fought off police charges of arson, but his insurers’ lingering doubts over his innocence have since tied up a payout that could exceed $200,000.

Which is why, last December (2006), Nathan travelled across the US and paid $1500 to have his brain scanned. “We provide a service for people who need to prove they are telling the truth,” says Joel Huizenga, a biologist turned entrepreneur and CEO of No Lie MRI of Tarzana, California.

In what amounted to the world’s first commercial lie-detection test using function magnetic resonance imaging (fMRI), technicians at No Lie mapped blood flow within Nathan’s brain while he answered a battery of questions about the deli fire and compared the results to control tests during which Nathan was asked to lie.

Think of a card

The differences in the way his brain responded to these tasks appear to confirm his innocence. Huizenga says No Lie is now working with a second client and he expects many more. Another group is planning to launch a similar service in Massachusetts.

Although fMRI has long been touted as a potential lie detector, the apparent emergence of an fMRI truth-telling industry in the US has come as something of a surprise – and one that not everyone finds welcome.

“I want proof before this gets used, and proof is not three studies of 40 college students lying about whether or not they are holding the three of spades,” says Hank Greely, director of Stanford University’s Center for Law and the Biosciences in California. Greely was among the experts who raised concerns about the technology during a special panel on lie detection held last week in Cambridge, Massachusetts.

According to panellists, limited studies on the validity of fMRI as a “truth detector” take no account of how results may be affected by age, intelligence, mental health and tricks that subjects may use to fool the machine. “There is an incredible hunger to have tests to separate truth from deception, science be damned,” warns neurobiologist Steven Hyman at Harvard University, in Cambridge, Massachusetts.

Potential customers

That hunger very probably extends to the US military. Jonathan Marks, a bioethicist at Pennsylvania State University in University Park recently saw a copy of a document by a US government interrogator that describes the use of fMRI as a screening tool. The document, archived at the Hoover Institution, a conservative think tank, will not be accessible to the public until 2010. It suggests fMRI has been used to examine the responses of suspects' brains to keywords that could betray knowledge of enemy activity. Documents obtained by the American Civil Liberties Union are similarly suggestive.

However, in an interview with New Scientist, officials at the Department of Defense Polygraph Institute denied any knowledge that fMRI has ever been used by the government or military for interrogation.

Sitting in the audience during the panel, Huizenga, who counts governments as well as individuals among his potential customers, appeared undeterred by scientists’ concerns. The use of fMRI for “truth verification” rather than lie detection is benign, he argues, as well as less subjective than the widely used polygraph test.

“If someone is trying to convict you of some heinous crime, we think you should have every means available to defend yourself,” he says.