The study found that stopping an action required three key brain areas to communicate with eight other areas. Previous research had suggested fewer areas were required.
The team also found that all the communication had to occur within about one-tenth of a second of when a participant saw the cue not to move their eye. After that, a signal has already been sent to the eye muscles and there is no way to stop it, Courtney says.
This lag is why we experience that awful, fleeting moment when our brain knows we shouldn’t stomp on the gas, but our foot does it anyway. “If the signal has already been sent you can watch it happen without being able to stop it,” Courtney says.
The brain’s stop system appears to be involved in a lot more than just controlling our bodies. “It’s not just about stopping your foot or your eyes, it’s about changing your plan about anything,” Courtney says.
One function of the brain systems that stop an action may be helping us avoid danger, says Russ Poldrack, a professor of psychology at Stanford University who was not part of the study.
“People now think that some of these same systems are involved in being more cautious in making choices, taking fewer risks,” he says.
Also, there’s growing evidence that these systems are faulty in people who have suffered brain damage or who abuse drugs, Poldrack says, adding that years ago, his lab did a study of people who take methamphetamine.