here thats called having mass (more than one person) hallucinations and delusions where one person may start out having them but others follow suit. its also called shared hallucinations and shared delusions.

I dont have that problem but we do treat others here that do. one time some people in the mental ward were maknig fun of this couple that had this problem. the couple lived together and were so bonded in their love and togetherness that many times had the same problems as each other. So we took the unit out side for a picnic and group session. first we had the picnic. then while everyone was sitting arount talking one of the therapists acted like they were concentrating on a special spot in the sky. took a while and someone finally asked the therapist what they were looking at. he told them "sorry theres a blip in the sky over there that keeps distracting me. its right their pointing see it" there was no blip we had planned this activity. but soon many in the group were saying oh yea there it is, I see it, its kind of silvery, where? oh yea now I see it...After we were all done eating and moved on to the group session we asked them how many actually saw the blip and how many were just agreeing so they would not be left out. All raised their hands saying they actually saw the blip. we let them know there was no blip. some turned around to confirm this. many laughed. some were relieved there were no alin blip over there in the sky. then we told them this was an exercise on how mass delusions and hallucinations such as our couple here have. they believed us because after so much time on the unit you begin to connect, trust and bond with each other and in doing so its very easy to fool our minds into believing that which is not true and does not exist. this group of people never again harrassed the couple again about their shared problems again.