Are motion detectors useful in paranormal investigations?
What exactly can a motion detector pick up while in use?
I always thought they could only pick up solid mass objects.
But if your using a motion detector ( in a controlled setting) and there is no solid mass passing in front of it and it alerts you that someones there and yet its impossible that anyone was there, what set it off?

I would think that it would be a good alarm to see if anyone is trying to mess with you during an investigation to fake evidence, but as far as picking up the paranormal it seems unreliable.

I also agree that I don't think they would be useful for an investigation. I know many motion detectors go off for no reason at all, so you could never be sure that it they are useful.

We used one once on investigation. The alert on it will blow your ears
away. I am more in favor of wind chimes. True they can move with the slightest breeze but I would be looking for movement too hard to be caused by a draft.