Old school horror flicks relied less on shock than on atmosphere. As I was watching The Pit and the Pendulum today, a Roger Corman guided Vincent Price vehicle drawing from Edgar Allan Poe, I realized that its slow pacing was not antiquated, but intentional mood-setting. This was something meant to be shown in a theater on the big screen, not at home on a television. Imagining myself in a dark theater surrounded by the sights and sound on screen, rather than my living room and all its distractions, the lowing cellos of the soundtrack, lush torchlit interiors, and creaking doors evoked a vividly sinister mood.
When blood and gore are used sparingly, their appearance on the screen attains special power. For instance, the great fifties Hammer reboot of Dracula, The Horror of Dracula, features very little screen time for the great Christopher Lee as Drac. It's the threat of his appearance that brings so much tension, and when he finally bares his teeth, it's quite frightening.
Of course, when we think of classic horror, our minds immediately conjure up images of the Universal films of the 1930s. Last Halloween I sat down and watched many of them for the first time, and was amazed at how well so many of them stood up. The 1931 James Whale adaptation of Frankenstein was especially good, in that it managed to create both sympathy and revulsion in the audience for the monster. This scene from Dr. Jekyll and Mr. Hyde, from the wondrously naughty pre-Code years, is more than steamy by today's standards.
Modern horror can give us much more graphic images than the films of the past, but their ability to powerfully evoke moods of dread and suspense ought to be more studied by the film directors of today.