Making sure you get the joke

It is one of the vanities of audiences that they don't need instructions for a work of art. It's all meant to be much more instinctive and easy than that - a relationship which just unfolds naturally.

It is one of the vanities of audiences that they don't need instructions for a work of art. It's all meant to be much more instinctive and easy than that - a relationship which just unfolds naturally. We flatter ourselves that we're sophisticated enough to cope with aesthetic unfamiliarity, and we like the idea that, given a bit of time, we can sort out how a thing works. And, if it doesn't work, we're naturally inclined to blame the manufacturers rather than taking the responsibility ourselves - even if we're engaged in the aesthetic equivalent of trying to use a hair-dryer to cook broccoli.

Of course, with some forms of high art this doesn't greatly matter. A conceptual installation can afford to be loftily indifferent to end-user satisfaction, since it doesn't depend on this for its continued existence. So what if 90 per cent of purchasers walk away baffled? It's only going to make the other 10 per cent feel even better about the product. But more commercial forms of art - film and theatre in particular - are generally required to be a little more down-to-earth about such matters.

One of the best-known examples of a work that was saved by its instruction leaflet is currently running in London. When A Funny Thing Happened On The Way To The Forum was on its out-of-town try-outs in America in 1962, audiences were distinctly lukewarm about the show. At a time when the musical had aspirations to higher things, this celebration of burlesque didn't come across as cheerfully nostalgic, rather as cheesily archaic. But then, not very long before the Broadway opening, Sondheim added the song "Comedy Tonight" - a list of ingredients which, effectively, told audiences how they were supposed to react. "Old situations, new complications... nothing portentous or polite" sang Pseudolus the slave, defusing the faint squirm of embarrassment caused by the show's rimshot comedy.

Among the adjectives used to describe what was in store for the audience were "appalling", "peculiar", "repulsive" and "erratic" - a striking case of raiding your critics' ammunition stores before the battle begins. It worked. Groan if you want to, this song reassured audiences, but groan with us, not at us. And Broadway audiences happily obeyed.

It's not strictly necessary any more I suppose but, as audiences of the National's current revival regularly demonstrate, the song still works as a way of frisking members of the audience for sharp objects, and disarming them, before the evening really begins.

Matters are generally more subtle with movies, though not always. Jean Renoir's film La Règle du Jeu begins with an admonitory title card that reads: "This story is intended as entertainment, not social criticism" - a wonderfully sly instruction that both has its cake and eats it. "Relax," it really says, "I'm not going to lecture you. You're allowed to laugh." But, just as when you say to someone "Don't think of a white polar bear", the prohibition neatly summons the very thing it sets out to forestall. In similar fashion, Robert Bresson opens his film Pickpocket with a solemn epigraph which announces that the film is not a thriller (" ce film n'est pas du style policier"), though in this case you get the feeling that he really means it. "Sit up straight and stop chewing gum", this set of instructions effectively declares, "you're not here for cheap escapism".

Such explicit user's manuals are rare, though. Most directors understand that the opening moments of a film - either the credit sequence or the first live-action frames - can be made to work on the audience subliminally, adjusting their expectations to create a climate in which the film can succeed. As the film critic David Thomson once wrote of the unconventional opening of Citizen Kane - "it's teaching us how to know it".

Coincidentally, there's another object lesson in the virtues of clear instructions a short walk away from the National Theatre. The Design Museum is currently showing an exhibition of the work of the designer Saul Bass - creator of some of Hitchcock's and Scorsese's best credit sequences. The exhibition is a good demonstration of the way in which an audience can be marshalled to face in the right direction before it is even aware that it is being worked upon. This isn't as obvious as it is with Sondheim's "Comedy Tonight" but the best of Bass's credit sequences are performing exactly the same task of audience tuition, ensuring that we don't end up blaming the film for not doing something it was never designed to do. Naturally, being vain, most of us don't even notice that we're actually following the instructions.