The Arts: Theatre: And now for the commercials... Cinemas do it, television does it, so why shouldn't theatres tempt audiences with trailers?

TRAILERS ARE an absolute a staple of cinema, and now somethingrather unusual is happening at the Young Vic. Those with tickets tothe RSC Macbeth starring Antony Sher and Harriet Walter are beinginvited to turn up half an hour early and, before taking their seatsin the main house, to check out the studio. There, they'll bepresented with an extended trailer for the latest production byPrimitive Science, the award-winning experimental company behind thevisually exquisite Icarus Falling, which enjoyed a sell-out run atthe Museum Of... in London last year.

Exactly which bits of the new show, Poseidon, will be on view inthe 15-minute taster had not been finalised last week, but even ifthe potential clientele only gets to see the audacious centrepiece -a wall of cascading water through which the action is observed - it'slikely to send them scurrying back to the box-office to book aticket.

According to Boz Temple-Morris, the company's producer, the ideaof staging something akin to an extended advert was mooted at theoutset of the project. The Young Vic offered the ideal venue in whichto try to catch the attention of the sort of punter who wouldnormally have to be dragged kicking and screaming to see a fringeshow.

"It seemed like such an obvious thing to do," Temple-Morrisexplains. "We were amazed that no one else had tried it. It doesn'tcost anything because the performers and crew are there anyway andthe potential benefit is enormous."

Which begs the question: why does the idea of a theatre trailer -anything from an excerpt to a more substantial mini-version - seem soradical when it clearly smacks of commonsense? True, there arecertain aspects of Primitive Science's Poseidon adventure that arenot easily replicable: it relies on two auditoria, and on audiencesbeing bothered enough to make a slight detour. But the principle isrobust enough to withstand different kinds of execution.

Why couldn't a company that was going through the final stages ofrehearsal, for example, pitch up at its prospective venue or atanother amenable space to whet theatre-goers' appetites for itsforthcoming attraction? A far-sighted company might even get in thehabit of trying out snippets of a work-in-progress prior to thecurrent presentation.

There are evidently practical hurdles that would need to beovercome, not least persuading theatre managers to be receptive. Butthe most obvious barrier is psychological: why would anyone wish toadopt a form so indelibly associated with cinema? The comparisoncould only work to theatre's disadvantage, surely. Two hours' worthof finished, multi-million pound product, edited down using thelatest post-production techniques, versus a handful of thespiansjumping from one section of dialogue and/or movement to another.Picture a bloke off-stage rasping deep-throatedly into a microphone,"From the makers of last year's touring two-man Macbeth comes a taleof greed, treachery and anti-Semitism in 16-century Malta..." It'senough to make the humiliation of appearing in The Bill seem likeparadise for actors, and a night in front of the telly the only saneoption for audiences.

Unless, that is, theatre practitioners took the idea, discardedwhat wasn't needed, and started afresh. Boz Temple-Morris promises aseries of elliptical pointers rather than a crude overview. Thephysical immediacy of performance, combined with the flexibility thatstagework demands of actors, would seem conducive to potent forms ofself-advertisement that could stand up as artworks in their ownright. The lack of gloss and polish would trumpet one of theatre'schief strengths: its power to suggest, and to get audiences to supplydetails with their own imaginations.

During the Edinburgh Festival, the streets throng with youngcompanies attempting to entice the public to see their shows. InLondon, the odd bit of leafleting is as visible as it gets.Meanwhile, it's not uncommon to be the only spectator at a fringeshow, while a staggering number of people seem prepared to gawp atwode-covered human statues in Covent Garden.

Sooner or later, that cautious curiosity, that desire to catch aglimpse of what a performance is like before putting money in thepot, is bound to be answered by new technology. Companies willincreasingly be able to trail their work on the internet using multi-media gadgetry. But to borrow the accoutrements of film without firstexploring the theatrical possibilities recognised by PrimitiveScience would be like visiting the seaside and stopping at theshoreline. Time, perhaps, for theatre companies to take the plunge.

`Poseidon', The Young Vic, London (020-7928 6363) to 27 May