Starlock
There really isn't any way to prove - in a scientific sense- that psychic vampirism does or doesn't exist. It's a non-falsifiable concept, so I'm not sure what you're looking to gain from this. Some aspects of psychic vampirism have a valid basis in human psychology, but it certainly isn't called that; people pick up and transfer emotions and moods all the time. I haven't been keeping up on that research though as it isn't my prime field, but I do recall reading an article on it some time in the last year.
I agree, however I think the basis for the experiment was that the self-proclaimed vampire in question felt he had a physical manifestation of his powers, not a solely psychic one. I remember the term "shape-shifter" being used.