Here’s a word we don’t use to often: Vigilance. University of Cincinnati professor Joel Warm defines it as our ability to spend long periods of time paying attention to routine tasks, which sometimes require quick action. And, if you think about it, we rely on all sorts of people to be vigilant, including air traffic controllers, pilots, truck drivers, and hospital personnel. 

But, no one’s studied how long the human brain can stay on-task when they’re in those kinds of situations. So, Dr. Warm gave a group of volunteers a test designed to gauge their attention spans. While the volunteers monitored a computer screen, the researchers used transcranial Doppler sonography – or TDS - to measure how fast blood flowed to the parts of the brain responsible for mental focus. The faster the blood flow, the harder that area is working. The result: Most people began to lose focus in as little as 10 minutes. In fact, the best performers in the study maintained high levels of concentration for 40 minutes - but no one topped that mark.

What’s this mean to you? In a high-vigilance job like monitoring a nuclear power plant, TDS could be used to determine when someone needs a break. 

For the rest of us, it backs up the old advice that “taking 5” at least once every hour will make us more productive, and less prone to mistakes.