An unusual trial is underway at the Wright-Patterson Air Force Base, near Dayton, Ohio. An airman sits at a monitor in a laboratory, wired up with electrodes, his jacket slung over the back of his chair. Plane-shaped icons keep entering his airspace. He has to decide whether each incoming plane is a friend or a foe. If it’s a foe, he must send a warning. If it flies off, fine. If it doesn’t, he must bring it down. The lab is silent, apart from the bleeps as he hits the buttons, and the smash as a software missile destroys an uncooperative plane.

The Wright-Patterson base is rich in aviation history. In and around this area, Wilbur and Orville Wright conducted pioneering experiments into flight. What they helped to start continues here, at the Air Force Research Laboratory (AFRL). Now the AFRL includes the 711th Human Performance Wing, whose mission is to “advance human performance in air, space and cyberspace”.

The aim of the trial today is to investigate whether stimulating the brain with a mild electrical current can improve the performance of military personnel. Will it work?

Trans-cranial direct current stimulation (tDCS) has been investigated as a possible treatment in healthcare for decades. In the 1980s, for example, it became clear that applying mild electrical currents to the brain could help patients with severe depression for whom the drugs did nothing.

Yet it wasn’t until the 2000s that neuroscientists realised tDCS could change the brain functioning of healthy people – a discovery that got the military interested.

“We began noticing a lot of the medical literature suggesting that cognitive functioning could be enhanced,” says Andy McKinley, the US military’s principal in-house tDCS researcher, who is now conducting trials. “We began thinking: if it could help with those healthy participants, it could potentially be an intervention tool we could use here in the military to help advance cognitive function.”