People who were deemed impulsive did indeed have shorter time intervals between their conscious awareness of the intention to act and the moment of action. The more impulsive they were, the shorter the interval.

“It might suggest that maybe impulsive individuals have less time to inhibit or control their actions,” says Caspar.

Aaron Schurger at the Swiss Federal Institute of Technology in Lausanne, who has worked on understanding the implications of the Libet experiment, cautions that any conclusions depend on how you interpret the various signals. His own work suggests that the readiness potential is not a signal of the brain getting ready to act, but rather a signature of random neural noise that accumulates and then crosses a threshold, making movement possible.

But many neuroscientists still favour Libet’s interpretation of the readiness potential. In that case, Schurger says that the study shows that “impulsive people have less time to ‘veto’ their actions since the decision to act happens much closer in time to the action itself”.