Francis Shen of the University of Minnesota Law School, who is chairing a session on neuroscience and the law at a meeting of the Cognitive Neuroscience Society in San Francisco this week, said the falling costs of functional magnetic resonance imaging, EEG and other brain scanning techniques would one day make it more practical for this type of evidence to show up in court.
Anthony Wagner, a cognitive neuroscientist at Stanford University, and colleagues outfitted study participants with digital cameras around their necks that automatically took photos of the participants' everyday experiences. Over a multi-week period, the cameras yielded 45,000 photos per participant, Wagner said.
Wagner's team then took brief photo sequences of individual events from the participants' lives and showed them to the participants in the fMRI scanner, along with photo sequences from other subjects as the control stimuli. The researchers analyzed their brain patterns to determine whether or not the participants were recognizing the sequences as their own.
"We did quite well with most subjects, with a mean accuracy of 91 percent in discriminating between event sequences that the participant recognized as old and those that the participant perceived as unfamiliar," Wagner said
"These findings indicate that distributed patterns of brain activity, as measured with fMRI, carry considerable information about an individual's subjective memory experience -- that is, whether or not they are remembering the event."