For the first time, researchers have managed to measure the so-called readiness potential outside of a lab setting and in its extreme. To do so, they picked one of the most heart-pumping settings you can imagine: a 192-meter bungee jump.

Credits: Tambako_The_Jaguar.

The readiness potential, also called Bereitschaftspotential (or BP, for short), has given researchers a lot of headaches. It’s essentially a minute electrical voltage shift in the brain that indicates an upcoming willful act. Basically, when you decide that you will do something, even before that decision becomes conscious, your brain sends out an electrical signal. This activity was first reported in 1964 after careful experiments carried out by German researchers.

Since then, numerous trials have studied the effect but, so far, none of them successfully ventured outside the lab, and for good reason: the electrical signal is extremely small.

The BP is ten to one hundred times smaller than the α-rhythm, the neural oscillations detected by an EEG. It measures only a few millionths of a volt, which means makes it extremely difficult to measure.

However, Surjo R. Soekadar, psychiatrist and neuroscientist at the University of Tübingen, and his doctoral candidate Marius Nann were able to pull it off.

They convinced two semi-professional cliff divers to have their brain waves recorded before jumping from the second highest bungee jumping platform in Europe.

After only a few calibration jumps, they were able to identify the readiness potential beyond the shadow of a doubt. In other words, they were able to see when the subjects decided to jump.

“Once again, the current experiment shows that the boundaries of the possible are shifting and that neurotechnology might soon be part of our everyday life,” Soekadar says. “The small number of jumps necessary for the experiment shows that the readiness potential prior to a bungee jump is very well expressed”, Nann explains.

This is, for starters, a technological breakthrough. It shows that at least under some conditions, BP can also be measured outside of a lab setting, which lays a foundation for future studies to build upon. But it could have a deeper meaning.

BP has been studied in relation to our free will. A series of experiments in the 1980s found that BP happened about 0.35 seconds before subjects consciously decided to do something. Benjamin Libet, who carried out those studies, concluded that we have no free will in the initiation of our movements, only an ability to veto these movements (a “free won’t”). Now, more and more evidence is building up against that particular interpretation.

The modern understanding is that while we don’t have absolute freedom, we have some degrees of freedom, even though we might not be aware of that. This study and future work based on it might finally settle that debate.

Journal Reference: Marius Nann, Leonardo G. Cohen, Lüder Deecke, Surjo R. Soekadar. To jump or not to jump: The Bereitschaftspotential required to jump into 192-meter abyss. doi: https://doi.org/10.1101/255083