Idk but it's a flawed and baseless assertion anyway. Some people do things that others literally won't. Where does this "duration" concept come from? lmao it's nonsense. If you run into a burning building and I don't... then you were brave and I wasn't. And you sure as shit weren't brave for 5 minutes. Hardly anything I would call brave is likely to last 5 minutes, that's insanely long. Anyway, I would argue that the "brave" part is the moment you decide to take action... after that you're in full adrenaline and concentration mode, and no longer feeling fear.