Of all the ghouls that haunt Halloween and popular culture, vampires are one - at least in notoriety - that never seem to die, and a Purdue University professor has some ideas why.
"Vampire stories have been around for thousands of years. Even before biblical times there was evidence that people believed in vampire-like creatures," says James Nairne, a professor of psychological sciences.
Scholars who study the vampire myth attribute its longevity partly to the dual nature of fear and fascination, says Nairne, who teaches a course on the psychology of the supernatural.
"In order for a supernatural concept to last, it must be a member of a natural category," he says. "Vampires are like people. This permits humans to draw inferences about how vampires might think and act. At the same time, supernatural concepts violate features of their natural category. Vampires are like humans, but unlike humans, they are dead and drink blood. If too many of these features are violated, the supernatural concept will not be believable and will not last."
These aspects make vampires both appealing and disgusting to the human mind.
Humans have a natural aversion to things that are dead because bodies carry diseases, and our brain is wired to use this fear to avoid those diseases. Vampires are also predators, another thing humans are wired to avoid, Nairne says.
"Death is very difficult for us because we cannot easily process the idea that a person no longer exists," Nairne says. "Vampires activate disgust in our minds because we are afraid they may contaminate us, yet we are drawn to them because they embody the idea that the soul can continue to exist after death."
Nairne, who has traveled twice to the home of Dracula in Transylvania, Romania, says people also are attracted to the special powers of vampires, such as superstrength or the ability to read minds.
"We find this attractive because then vampires appear to have a power over us. These special abilities simultaneously create worry and fascination. We are drawn to them much in the same way we might be drawn to celebrities.
"Because of this, it is likely that vampires will continue to live on for years to come."