Film is a medium best savoured with the lights off, but modern cinema audiences have their work cut out trying to remain in the dark. Anyone hoping to extricate maximum enjoyment from a film must avert the eyes from all pre-release publicity - especially trailers. The modern trailer strikes with precision, annihilating the expectation of excitement, the bliss of ignorance. Where once a trailer was a sophisticated tease, it has now become a brutal compendium of potted highlights, filleting the movie it is meant to be promoting, and leaving only scraps for the luckless viewer to pick over.
I experienced this recently when I almost saw the trailer for Spike Lee's thriller Inside Man. As soon as it dawned on me that the movie looked intriguing, with an impressive cast (Clive Owen, Denzel Washington, Jodie Foster, Chiwetel Ejiofor), I screwed my eyes shut and clamped my hands over my ears. Other audience members may have interpreted this as a psychotic episode. For me it was insurance to protect the day when I see Inside Man. It may turn out that the film is dreadful, but at least my viewing experience will be unpolluted by knowing who did what to whom and why before I've even bought my ticket.
Such trailers are especially problem- atic with plot-driven pictures. The trailer for Syriana, for example, shows what happens to George Clooney's character halfway through the film, turning the moment in question from a bombshell to a squib. Anyone looking forward to V for Vendetta, written by the creators of The Matrix, should steer clear of that movie's trailers, which make explicit the fates awaiting minor characters. Even the modest plot twist in the recent Wallace and Gromit feature, The Curse of the Were-Rabbit, was ruined by the spoilsport who chose to let slip the identity of the were-rabbit in the trailer.
This trend has turned us into a nation of Cassandras, glumly watching scenes that we have learned by rote during the preceding months of promos. It wasn't always so. Look now at the trailers for The Wizard of Oz or Singin' in the Rain and you will be struck by the way they conjure the tone of those movies without obliterating their mystery and magic. The leisurely pace is surprising, too - and how refreshing to watch trailers not edited on the presumption that the audience comprises nothing but ADD sufferers.
In exceptional cases, the trailer itself can become an art form. Stanley Kubrick and Alfred Hitchcock were instrumental in creating some of the wittiest trailers ever made. Dr Strangelove was adver-tised with a breakneck collage of flashing words combined with snippets of dialogue to create new and surreal meanings; it may not have explained much, but you got a sense of that film's savage absurdity. Kubrick proved himself too clever for some with the trailer for Eyes Wide Shut: the 90-second clip of Tom Cruise caressing Nicole Kidman in front of a mirror as Chris Isaak sings "Baby Did a Bad Bad Thing" was blamed for promising a sex-ual explicitness that the film never delivered. What the dissenters missed was that this was perfectly in keeping with the whole film, which Cruise spends poised to consummate his desire for various women while being doomed to keep his fly wide shut.
It is Hitchcock, however, who remains the undisputed king of the trailer. He understood that a trailer must be a work of seduction and suspense; it should whet the viewer's appetite, but never sate it. Those in which Hitchcock personally introduces his own film exemplify the director's devilish sense of mischief. To promote North by Northwest, he glares at the camera and hawks the film as if it were a package holiday: "You don't find a tasteful little murder on every guided tour, do you? . . . For vacation romance, how about an amorous blonde like Eva Marie Saint? . . . Now for the climax of our tour - the serene nobility of Mount Rushmore . . ."
The possibilities open to this much-squandered species of advertising have never again been exploited as expertly as they are in the six-minute Psycho trailer, in which Hitchcock walks us through the film's eerily deserted sets, culmina-ting in the bathroom in Room One of the Bates Motel. There, he declares: "They've cleaned it all up now. There was so much blood . . ." before whipping back the shower curtain with sadistic delight. No one could ever make a trailer of this kind now. Audiences like to know exactly what is in store for them; gone are the days when a film could be sold as "the most unusual motion picture of the year", as Sunset Boulevard was. This suits the studios, which are also seeking to eliminate risk. The natural product of unquestioning audiences and unadventurous studios is a processed style of film-making that never strays from the familiar. Similarly, trailers are no longer signposts directing us into the murk of unknown pleasures, but sat-nav systems, mapping out every narrative manoeuvre.
If you crave innovation in this area, your sole refuge is the online craft of spoof trailer-making, where smart alecs create mock-up jobs from existing footage. Currently all the rage are the Brokeback Mountain parodies which impose a gay narrative on straight movies - Brokeback to the Future and Star Wars: the empire brokeback being two of the wittiest (these are available on www.youtube.com ). But it must sound a death knell for creativity in the modern trailer that the cleverest ones are pushing a sensibility rather than a product, and will not be coming to a cinema near you any time soon.
To view a selection of film trailers, visit www.movie-list.com