"Sky divers will tell you it's the thrill, the rush, and a little element of fear that motivates them to push themselves to the extreme," he says.
Of course, some people would prefer to completely avoid those or any other scary flicks -- about one-third of the population falls into this category, says Sparks.
For them, there's no redeeming value to stories that leave them frozen with fear.
Sparks describes a woman in her late thirties who saw Silence of the Lambs, and found the film so terrifying that she didn't eat meat for the next six months.
When The Exorcist was initially released three decades ago, there were several cases of adults who experienced such high levels of distress that they needed to be hospitalized.
They thrive on the latest Friday the 13 movie or Stephen King novel.
But whether that fright is caused by watching a nail-biting horror movie, listening to a spine-chilling story, or prowling through a dark-as-night haunted house on Halloween, some people actually revel in feeling frightened.
In his studies of people who thrive on riding roller coasters, "there's almost nothing else, including sex, that can match it in terms of the incredible sensory experience that the body is put through." As for children, an event like Halloween can provide an enjoyable and safe way to explore and experience fear, knowing that the goblins and witches stalking their neighborhood are only make-believe.