Recently, 29 students from Northwestern University in Illinois planned a terrorist attack. Researchers from the university were subsequently able to learn details of the attack, even though the students never admitted to anything. How was this possible? Well, essentially, the researchers read the students’ minds. More specifically, they monitored their P300 brain waves – brief electrical patterns in the cortex, which occur when meaningful information is presented to someone with “guilty knowledge.” In this case, it was a mock planned attack, but the research team believe their process could be used to prevent the real thing.

The study involved attaching electrodes to the students’ scalps, then presenting them with a number of stimuli on a computer monitor. Those stimuli included the names of cities such as Boston, Houston, New York, Chicago and Phoenix, shuffled and presented at random. In almost every case, the name of the location of the planned attack evoked the largest P300 responses.

"Without any prior knowledge of the planned crime in our mock terrorism scenarios, we were able to identify 10 out of 12 terrorists and, among them, 20 out of 30 crime-related details," said J. Peter Rosenfeld, professor of psychology in Northwestern's Weinberg College of Arts and Sciences. "The test was 83 percent accurate in predicting concealed knowledge, suggesting that our complex protocol could identify future terrorist activity."

Given that the students only had 30 minutes to hatch their dastardly plan, it is assumed that real terrorists, who would put much more time and effort into their plan, would give even stronger responses.

Of course, using technology to discern what people are thinking is nothing new. Besides the highly-controversial polygraph, people have experimented with lie detectors that read facial gestures, glasses that indicate lies through voice stress analysis, and voice stress reading devices for screening passengers at airports. Even P300 waves have been studied since the 1980s, although current technology has made them a more viable option.

"Since 9/11 preventing terrorism is a priority," Rosenfeld said. "Sometimes you catch suspicious people entering a building. You suspect that they're terrorists, and you have some leads from the chatter. You've heard they're going to attack one city or another in one fashion or another on one date or another. Our hope is that our new complex protocol – different from the first P300 technology developed in the 1980s – will one day confirm such chatter in the real world."