From Science Daily, 19 Feb, a report on the recent symposium Is There Science Underlying Truth Detection? sponsored by the American Academy of Arts and Sciences and the McGovern Institute for Brain Research at MIT. It does a good job at summarising some of the practical, legal, ethical and theoretical issues surrounding the use of fMRI for deception detection. Here’s an excerpt, but it’s worth reading in full:
The symposium explored whether functional magnetic resonance imaging (fMRI), which images brain regions at work, can detect lying. “There are some bold claims regarding the potential to use functional MRI to detect deception, so it’s important to learn what is known about the science,” said Emilio Bizzi, president of the American Academy of Arts and Sciences, an investigator at MIT’s McGovern Institute for Brain Research and one of the organizers of the event.
[…] In 2005, two separate teams of researchers announced that their algorithms had been able to reliably identify “neural signatures” that indicated when a subject was lying. But the research, conducted on only a handful of subjects, was flawed, Kanwisher said. Subjects were asked to lie about whether they were holding a certain card or whether they had “stolen” certain items. These are not actually lies, she pointed out, because subjects were asked to make such statements. “What does this have to do with real-world lie detection? Making a false response when instructed isn’t a lie.
[…] In addition, the subject may not want to cooperate. “FMRI results are garbage if the subject is moving even a little bit. A subject can completely mess up the data by moving his tongue in his mouth or performing mental arithmetic,” she said. Testing also poses problems. To ensure accurate results, fMRIs would have to be tested on a wide variety of people, some guilty and some innocent, and they would need to believe that the data would have real consequences on their lives. The work would need to published in peer-reviewed journals and replicated without conflicts of interest.
In short, Kaniwsher said, “There’s no compelling evidence fMRIs will work for lie detection in the real world.”