Researchers from the John Hopkins University took a glimpse on what is happening in the human brain during a voluntary decision to act.

Their study, published in the journal Attention, Perception & Psychophysics, revealed that two brain regions are responsible for free will.

In order to observe what is happening in the brain during free choice, the researchers devised an experiment that tracks an individual's focus of attention without the use of intrusive cues or commands. Participants of the study were left alone in a MRI scanner while watching a split screen of rapidly streaming of colorful numbers and letters past on each side.

The researchers asked the participants to pay attention to one side of the split screen for a while, and the shift to the other side. The participants were left with the decision when to shift their attention to either sides of the screen. The experiment occurred for an hour and the participants must have been switching their attention to either screen a dozen times.

While the participants were undergoing the experiment, the researchers closely monitored their brain as they watch the stream and before and after they switch their focus. For the first time, the researchers were able to see what happens in the human brain when a free choice is made, and what happens during the lead-up to that decision.

When the participants switch their attention from one side of the screen to the other, researchers noted an activity in their parietal lobe located near the back of the brain. On the other hand, during the period of deliberation, or when the participants were thinking when to switch, an activity is observed in the frontal cortex and basal ganglia. The activity in the frontal cortex occurred in the areas involved in reasoning an movement, while basal ganglia is the region deep in the brain responsible for a variety of motor control functions including the ability to start an action.

According to a press release, the researchers observed that the activity in the frontal lobe began earlier than it would have the participants had been told to shift attention. This clearly demonstrate that the brain was preparing a purely voluntary action rather than merely following order.