This sounds like something a clever prosecutor, detective or U.S. intelligence official might find useful. Who knows the clever ways some of them might have been taught similar to this methodology.
Seems equally possible the formula <+ +> + <- -> might prove useful in scientific experimental outcomes as well. Can't rule out the possibly a fake mentalist couldn't use it to their advantage either. Sure a lot of clever people out there. Certainly not what I could have come up with. That's for sure!