Music is also important, like the pulsating theme of the movie, "Jaws," as the white shark leaps out of the water.
Sometimes the sensation is tactile, when walking through an unstable platform in a fun house.
Roller coasters are the ultimate thrill ride. "Where else are you expected to throw your hands in the air and scream at the top of your lungs?" Farley asked.
"The intensity factor is important," he said. "On thrill rides, they really jerk a person around. They rotate the body and change the G force and people are screaming. You don't know what's going to happen next."
Novelty and contradiction is also a factor in fear -- a clown who kills or a child who is a monster.
Movies and books that exploit the most basic of human fears come dangerously close to reality. And experiencing that horror as a child can be a dress rehearsal for facing fear in the adult world.
"We have a lot of reason to be fearful in the world," said Farley.
"How could Jeffrey Dahmer kill and eat those boys and store their body parts in the refrigerator?" he asked. "Gadhafi is dead today, but in the early days of his dictatorship he hung protesters from lampposts."
Children have an uncanny attraction to frightening stories and psychologists say they project their fears and come to terms with them through stories.
Some of the most popular children's fiction involves ghost, vampires and skeletons. Harry Potter enthralls readers with witches and warlocks. R.L. Stine's original "Goosebumps" series -- "Welcome to Camp Nightmare" and the Abominable Snowman of Pasadena" has entertained teens for decades.
Some of the original Grimm Brothers' fairy tales, culled from folk stories that had been recited over generations, were gruesome, including rapes, incest, child murder and incessant bullying, according to the trivia website, The List Universe.
In "Snow White," the queen asks for the young maiden's liver and lungs, which she intends to serve up for dinner. In the end the wicked queen dances in red hot iron shoes.
The original "Sleeping Beauty" is bitten and then raped by the king (not kissed by a prince), and she gives birth to his two children in her sleep. One of them sucks off the flax that has kept the princess asleep for 100 years, waking her up.
The "Pied Piper" actually entices the village children to follow him to a river, where they all drown. And the step-sisters of "Cinderella" cut off parts of their own feet to fit into the glass slipper.
"Fairytales are a path to dealing with fear, to figure out how it works, what it is and recognizing it," he said. "Pulling your head out of the sand when you are surrounded by horror or fearsome things has a high survival value."
The same may be said of horror movies -- the terror that reflects life's real fears is the worst. One filmgoer said the 2011 film "Contagion," about a lethal pandemic, was particularly frightening.
"It's not the horror movies that scare me," she said. "It's movies about things that seem like they actually could happen. As a germ-a-phone, that was terrifying."
Others have given up the genre forever.
"I have a theory," said Wheeze Carlson, a 59-year-old from Michigan who was raped as a girl. "Only people that have never experienced true fear and terror like that stuff. The rest of us never want to ever revisit that emotion again."
And even those like Michele Sinesky who crave horror movies, have their limits.
"I avoid human monsters at all costs," she said. "And I hate slasher movies."