If director William Castle had been born 50 years earlier, he'd have had a career with the circus. An old-fashioned, cigar-chomping showman and huckster, Castle was widely renowned throughout the 50s and 60s as the PT Barnum of horror. Since he knew most of his films were rubbish, Castle jazzed them up with a series of gizmos and gadgets that took audience participation to new heights.
For "Macabre", Castle's Lloyds of London insurance policy guaranteed horror fans that they'd receive $1000 if they died of fright during the movie. Hearses were parked outside the cinema in preparation for the corpses and nurses (well, pretty girls dressed in nurses uniforms) were stationed in the foyer. Surprisingly, he kept his no-claims bonus.
Castle took things a step further for "The Tingler", wiring certain seats in the auditorium to a mild electric current and throwing the switch as the film's title monster supposedly got loose in the cinema.
"More Startling Than 3-D!" proclaimed the ads for his next film, "13 Ghosts", where special "Illusion-O" spectacles were handed out to the audience so the ghosts could be seen (they didn't do very much, but no one worked that out until after the movie was finished).
In "House on Haunted Hill", he had skeletons whizzing over the audience's heads on wires as Vincent Price dropped his fellow on-screen characters into a tub of flesh-burning acid.
After the runaway success of "Psycho", Castle pinched the plot for "Homicidal" and hyped the film by offering audiences a "Fright Break" two minutes before the movie's end. Anyone too scared to watch the final moments of the story could leave and get a full refund.
Then for "Mr Sardonicus" in 1961, Castle had the audience take a vote on whether the villain should live or die at the film's conclusion (the director was so sure about the results he only bothered shooting the more gruesome of the two endings).
If only today's promotional whiz kids had half as much imagination.