Jill Rosen in PhysOrg:
Johns Hopkins University researchers are the first to glimpse the human brain making a purely voluntary decision to act. Unlike most brain studies where scientists watch as people respond to cues or commands, Johns Hopkins researchers found a way to observe people's brain activity as they made choices entirely on their own. The findings, which pinpoint the parts of the brain involved in decision-making and action, are now online, and due to appear in a special October issue of the journal Attention, Perception, & Psychophysics. “How do we peek into people's brains and find out how we make choices entirely on our own?” asked Susan Courtney, a professor of psychological and brain sciences. “What parts of the brain are involved in free choice?”
The team devised a novel experiment to track a person's focus of attention without using intrusive cues or commands. Participants, positioned in MRI scanners, were left alone to watch a split screen as rapid streams of colorful numbers and letters scrolled past on each side. They were asked simply to pay attention to one side for a while, then to the other side—when to switch sides was entirely up to them. Over an hour, the participants switched their attention from one side to the other dozens of times. Researchers monitored the participants' brains as they watched the media stream, both before and after they switched their focus. For the first time, researchers were able to see both what happens in a human brain the moment a free choice is made, and what happens during the lead-up to that decision—how the brain behaves during the deliberation over whether to act.