'We're confident it's real': Arthur Aron is a psychologist who has discovered that blood-flows in the brains of people claiming to be in love after decades of marriage resemble those of new lovers. Romance may authentically survive: 'That's what the brain scans are telling us. People can't fake that.' 'Brain-Scan Lie Detectors Coming in Near Future,' runs a news story, cued by a San Diego company press release. Will they become part of legal routine, or will they flicker and fade, like the neural theology predicted ten years back? 'Brain scan of nuns finds no single "God spot" in the brain,' we have since been told. Some 17 years after its initial demonstration, fMRI - the 'functional Magnetic Resonance Imaging' technique for examining what is happening in the brain - has gained a lodgment in talk beyond the lab. Alluringly, it treats us to pictures. Carefully settle your head inside the tunnel of that $3 million machine, fix your attention on God or your spouse or your witness statement, and an activated magnetic field will be minutely deflected here and there, as blood moves towards areas where brain cells have been active: patterns that get translated into ever finer-grained screen displays. These supposed maps of thought have lent colour to such projects of the last decade as 'neuroethics' and 'neuromarketing'. (The latter took off five years ago, with a study comparing the way Pepsi and Coca-Cola affected the brain's 'reward centres'.) Traffic-light colour, most often: in the standard graphics, reds or greens are seen to inflame sundry patches of an isolated, ruckled grey mass with a slippery sheen.

LRB 8 October 2009 | PDF Download