The other day i thought of something interesting.
Some people claim they can see spirits as they wish and communicate with them. They also say they can see them as clearly as they can see normal people. So i thought, when you see moving objects, your eyes are fluidly following the object. When you try for example to make your eyes move from one point to another without following an object you will not be able to move them fluidly, right? So if you know a medium try that: ask them if they can prove to you that they can see spirits by asking the spirit to move in front of tem and see if their eyes follow as if there was really something.
As we know, its physically impossible for them to fake the fluid eye movement so it will prove they see something. The only problem is if the spirit is only in the persons imagination the eye can follow because it has been scientifically proven that in dreams eyes can easily follow moving objects.
Let me know if someone wants to try this experiment, id be really curious to see the results