I wonder how much of the documented improvement is placebo effect?
Even if it didn't directly improve focus it seems like it would be a great placebo. Nine volt batteries are probably commonly perceived as being powerful. They are used in stun guns, for example. You also experience unusual side effects after it's applied, further removing any doubt that something unique is happening to you.
> I wonder how much of the documented improvement is placebo effect?
I'm sure they controlled for that, as it is stupendously obvious and common to control for, and easy to do - just don't turn on the battery, or measure the effects of the current direction reversed (damages performance according to the other article).
Even if it didn't directly improve focus it seems like it would be a great placebo. Nine volt batteries are probably commonly perceived as being powerful. They are used in stun guns, for example. You also experience unusual side effects after it's applied, further removing any doubt that something unique is happening to you.