The software tries to detect whether, when the crime’s details are recited, the brain lights up in specific regions  the areas that, according to the technology’s inventors, show measurable changes when experiences are relived, their smells and sounds summoned back to consciousness. The inventors of the technology claim the system can distinguish between people’s memories of events they witnessed and between deeds they committed.

The Brain Electrical Oscillations Signature test, or BEOS, was developed by Champadi Raman Mukundan, a neuroscientist who formerly ran the clinical psychology department of the National Institute of Mental Health and Neuro Sciences in Bangalore. His system builds on methods developed at American universities by other scientists, including Emanuel Donchin, Lawrence A. Farwell and J. Peter Rosenfeld.

Despite the technology’s promise  some believe it could transform investigations as much as DNA evidence has  many experts in psychology and neuroscience were troubled that it was used to win a criminal conviction before being validated by any independent study and reported in a respected scientific journal. Publication of data from testing of the scans would allow other scientists to judge its merits  and the validity of the studies  during peer reviews.

“Technologies which are neither seriously peer-reviewed nor independently replicated are not, in my opinion, credible,” said Dr. Rosenfeld, a psychologist and neuroscientist at Northwestern University and one of the early developers of electroencephalogram-based lie detection. “The fact that an advanced and sophisticated democratic society such as India would actually convict persons based on an unproven technology is even more incredible.”

After passing an 18-page promotional dossier about the BEOS test to a few of his colleagues, Michael S. Gazzaniga, a neuroscientist and director of the SAGE Center for the Study of the Mind at the University of California, Santa Barbara, said: “Well, the experts all agree. This work is shaky at best.”

None of these experts have met the Indian inventors and the investigators using the test. One British forensic psychologist who has met them said he found the presentation highly convincing.

“According to the cases that have been presented to me, BEOS has clearly demonstrated its utility in providing admissible evidence that has been used to assist in the conviction of defendants in court,” Keith Ashcroft, a frequent expert witness in the British courts, said in an e-mail message.