What do you think about occurrences like Mass Hallucination in connection with UFOs and similar stuff?

Has ever anyone done Experiments in this field?

What do you think would happen if some one would invent a monster and tell the press he/she has seen it somewhere?
Not the usual stuff but something like a green 30ft Lobster, would there be people which would come forward and tell that they have seen the same creature?

Would this work the same way like when people (who are already believers) have started to see the Virgin Mary in a window or fence post?

In his book, “Flim Flam”, James Randi tells the story of how he was a guest on a radio talk show, and he MADE UP a UFO sighting he claimed to have had earlier.  He described it as a “V-shaped formation of triangular orange objects”.  People starting calling in, saying they were seeing the same thing!

And I remember reading once about a controlled experiment in hoaxing a group of UFOlogists.  I’ll have to hunt around and see if I can find an article on it.