In Richard Matheson's classic novella I Am Legend, a disease has turned mankind into ravenous, rabid vampires. The last human alive survives the plague because years ago he was bitten by a bat which gave him immunity.
The narrator, Dr. Neville, explains that vampirism isn't mystical, but scientific. The wretched creatures survive gunshot wounds because their blood has become a thick goo that clots immediately. So, wounds hurt, but won't kill them. Hence the need for a wide enough stake driven through the heart to slay a vampire.
The disease mutates the victims, causing their incisors to grow. Sunlight and garlic damage the bacteria in the vampire, and so forth. Since Dr Neville was a biological researcher, so he is meticulous with his observations.
The scientist notices that the vampires do not like seeing their own reflection in a mirror which repulses them.
Similarly, crucifixes repel the vampires, I think even the Jewish ones if I recall correctly.
Some vampires jump off buildings and begin flapping their arms like bats, but haplessly fall to the earth, only to be consumed by the other vampires awaiting them at street level.
There is no medical or biological reason for these behaviors. Dr Neville realizes that these vampires-- when they were human -- were conditioned by vampire folklore and stories of Dracula turning into a bat.
From Wiki:
"The vampires are affected by mirrors and crosses because of "hysterical blindness," in which the infected delusionally react-- as they believe they should-- when confronted with these items."
So, if a certain sector of society is "conditioned" to see a white light at the end of the tunnel, they will indeed believe they saw that illumination.
"He leaves on Thursdays a lot at 11 in the morning and doesn't fly back [from Oklahoma] until Monday afternoon. He is barely in the building."
Behold, life at the public trough.