FILM / A big hand for SFX: Adam Mars-Jones looks beneath Charles Russell's beguiling The Mask.

Any honest filmgoer, surely, will admit the profound pleasure to be had from special effects. It isn't just a matter of indulgent childhood memories, the first magical viewing of King Kong or The Wizard of Oz. 2001: A Space Odyssey, Brazil, Prospero's Books and The Naked Lunch are not what you think of when you think of special effects movies, but where would they be without their boxes of tricks?

The cinema's most distinctive poetry is the poetry of the impossible, and it isn't only commercial directors that have thought so. Even if the special effects are all that make The Mask worth seeing, that is still plenty. Effects remain Hollywood's trump card, sufficient guarantee that audiences will not indefinitely be seduced away by television or video games. To get statistical for a moment: a single company specialising in special effects (Industrial Light and Magic, responsible for the work on The Mask) has been involved in eight out of the 12 top-grossing films ever made. These days, it's the films that make the money without a special effects budget - Driving Miss Daisy, Enchanted April - that are the anomalies.

Over the last 20 years, there have been several distinct cycles of development in the world of special effects. The trend has been towards realism, with important exceptions: Spielberg's Close Encounters chose a dazzling vagueness over flat precision, and the effects in Coppola's Dracula were largely based on Victorian stage illusions (with some being realised in front of the camera, rather than in post-production).

For a time in the 1980s, hydraulics were in fashion. The disadvantage of this method was that it required close-ups rather than long shots, and rapid cutting rather than sustained takes. After Alien it became something of a cliche for monsters to be shown in brief glimpses out of spatial context.

Sometimes it seems that every film was a milestone. Beetlejuice demonstrated that effects could be an aspect of a film's art direction, enabling a director to put a distinctive styling even on monsters, and that audiences could tolerate a surprising amount of grotesqueness without losing sympathy for characters. Who Framed Roger Rabbit showed there was still life in animation, and Terminator II proved that computer-generated effects could hold their own on screen with live action. All these films have fed in to The Mask, and many others besides, but its director, Charles Russell, doesn't labour the influences. The most obvious one - Tex Avery cartoons of the 1940s - is announced in the decor of the hero's apartment, before his life is transformed by the discovery of a mysterious mask, a mask infused with the powers of Loki, Scandinavian god of mischief.

Whenever Stanley Ipkiss (Jim Carrey) puts on the mask after dark, it melds with his face, and gives him unlimited powers that are somehow the expression of a buried self. It certainly brings a buried self out of Jim Carrey, an agreeable enough performer but not a thrilling one in the normal course of things, who projects something quite different in his sequences as The Mask. He's not a constitutionally hyperactive comedian in the Robin Williams mould, and the energy of this strange persona - suave, romantic, both knowing and innocent - is all the more satisfying for that. The pistachio- green face, bald head, prominent cheekbones and vast teeth should be menacing, but this is a wholly beguiling performance. It's a mark of the film's success that it isn't easy to tell where acting ends and special effects take over.

Someone, perhaps Craig Stearns, the production designer, has chosen to make The Mask a sort of dandified 1940s Hispanic, complete with zoot suit and a love of Latin dancing. There seems to be no logic to this - though the period is right for Tex Avery cartoons - but it gives Carrey something very different from his Anglo-likeability to work with, his usual repertoire of wry expressions on a regular-guy face.

The revisionist historians at Industrial Light and Magic would have you believe that this is the first time their firm has provided illusion for a comedy. This claim at least recognises that Death Becomes Her, if as cartoonish as anyone could wish, wasn't actually funny, though it rather slights Who Framed Roger Rabbit.

But certainly there is a refreshing lightness of touch about The Mask. None of the other characters, for instance, seem to notice that The Mask breaks physical law at every possible point. Even policemen watching the security video after a bank robbery manage to ignore the intruder's kinetic vaudeville, his shameless mugging for the hidden cameras.

Every American film has to testify to an imaginary committee of the Senate and answer the question: What are you teaching our children? (Terminator II puts its android hand on its android heart and says: I teach the virtues of disarmament.) The compulsory moral of The Mask is, inevitably: it doesn't matter what special powers you have, what counts is who you are on the inside. The only sophistication the film can boast is that two women reassure the hero in these terms, and one of them is lying. The hero duly divests himself of specialness to please the woman who really means it, but audiences are likely to echo what Garbo said at the premiere of Jean Cocteau's Beauty and the Beast, and to plead: 'Give me back my Mask.'

(Photograph omitted)