ART REVIEW / Is there someone out there?: Video art can be repetitive, monotonous, pretentious too. And, as Tom Lubbock discovered, startling and disorienting

Video-art uses a familiar, friendly and above all normal medium, and that can be to its advantage. Certainly, whenever there's a television in an art gallery, people tend to gravitate towards it. But this popularity cuts the other way, too. It makes art-videos look inherently pretentious. Compared to most things you're likely to see in this medium, they come over as excessively demanding of attention, almost a deliberate frustration of usual video pleasures. And it's true - the hypnotically repetitive image, with the unbelievably monotonous voice-over - there are some bad times to be had with video-art. Still, a caveat is in order. One shouldn't be so bound to a sense of what's video-normal that all but its most familiar uses seem simply perverse.

But the proof of the pudding, of course . . . and at the moment, if you're interested, you're in luck. Its novelty notwithstanding, the form has already acquired its masters, or at least its star- practitioners, and by any reckoning Gary Hill and Bill Viola are two of them. Both these US video-artists happen now to have UK shows. Hill's at Moma in Oxford (moving on to the Liverpool Tate in February); Viola's at the Whitechapel Gallery (with another piece at Anthony d'Offay). And both have taken the art-video a long way beyond the stereotype. In some ways they seem to be up to the same things, but their similarities reveal distinctions.

One thing they both do, for instance, is to treat the television screen rather in the same way as modern painting treated the picture surface: not as a window to look through, but as a physical object - the tube, the box, used sculpturally. One might think of Dame Edna's telling remark, 'Oh I adore the television. It's such an attractive piece of furniture' - or of the little girl in Poltergeist, trapped inside the screen. Viola has a meditative piece, The Sleepers, consisting of five oil drums filled with water, with a monitor face-up at the bottom of each showing images of heads asleep - and you feel these heads to be within the monitors, deeply submerged. It's an effective though simple metaphor for the sleeping mind.

Hill, in a kind of equivalent piece, does something rather more complex. Inasmuch as It is Always Already Taking Place (his titles are sometimes like that, unfortunately) is a still-life arrangement of 16 naked television tubes, ranging in width from 23 inches to the size of a 5p coin, each transmitting the close-up image of a part of a body - chest, ear, elbow, foot, though it's not always clear what - lying still but clearly alive, breathing or twitching slightly. A metamorphosis occurs. The tubes become quasi-organs: screen equates with skin, flexes with veins or nerves, light-glow with life; the whole arrangement appears as not just a bank of monitors, but an alternative body system, broken up, dispersed, re-ordered, in which vision and sensation are somehow fused.

There's little doubt that video-art, even of this very 'fine' sort, has its endemic cliches. It tends to be drawn (to invoke Dame Edna again) towards the spooky - the edge of consciousness, the disembodied body, shrine-like chambers with dim, religious lights. And there's little doubt, too, despite the caveats above, that Viola is actually a pretentious artist. The piece at d'Offay, for instance, is an all too precious assemblage of resonant devices: a television showing a beating heart, a basin of water in front of it, an interesting stone, a spot-lit flask whose image is projected, via a camera obscura, on to a screen. Viola plunges into the big abstract nouns. The main piece at the Whitechapel is a huge triptych of screens, the left one showing a woman (his wife) giving birth, the right one showing a woman (his mother) literally dying before one's eyes. The spectacle wouldn't necessarily seem voyeuristic if the subject hadn't been drawn from a beginner's book of themes. But Viola seems stuck on the medium's amazing 'potential', and content then to exploit this in quite simple-minded ways.

Hill is much more inventive, especially in the relationships he creates between image and spectator. Learning Curve definitely deserves a mention here. A school desk is given a big fan-extension, finishing in a curving screen on which a wave endlessly breaks. It locks the sitter / viewer into the view. But - since the effects are not going to be easy to convey briefly, and are impossible to illustrate - I want to rush on to Hill's most astonishing work, Tall Ships. Envisage this. The view from the threshold is a corridor, 30 yards long, and almost pitch dark - except for small patches of dim light, at eye-level, at regular intervals along the wall. So you make your way along the corridor up to, say, the first of these patches. You see then that it's the miniature, motionless and blurry image of a person. There's no screen or frame around it - it's a projection from overhead - just this lit image on an otherwise dark wall. You stand looking at it. At this point an amazingly spectacular effect occurs. As if summoned by your presence (actually, because of a pressure switch under the carpet) the image comes to life: it turns round, looks up at you, and begins to walk towards you, growing dramatically in size as it comes nearer, seeming almost to walk out of the wall, and ends up standing before you, practically face to face.

There are 15 of these presences, people of both sexes and various ages and races, and with various ways of confronting you. Their gaze and gestures may say 'Well, here I am. What?', or 'Can I go now please?', or (a puzzled stare, as if answering the door-bell on a dark night) 'Is there someone out there?' One woman does a mime on the lines of 'Hang on, I'm sure I know you', and you can't help but grin back self-consciously. And so long as you stand there, they stand there too, doing what they do. But having watched enough, say you take a step back: almost at once, the figure turns its back and walks away, shrinking to its original, miniature blur - the homunculus back in its bottle, awaiting the next summons to life.

Spooky again, certainly, but the ghosts in this machine are really made to work. It's a nearly living gallery of portraits that 'seem to follow you round the room', and though you know the causes are mechanical, it becomes a doubtful point for the viewer who is in command here, you or the image. At least, it's difficult to treat these figures as merely images. You can control their behaviour in a limited way, but they face you like another consciousness. They're people who respond to your presence, but with whom (for of course they are only images) contact is absolutely impossible. All these ambiguous feelings come to a head in the heart-breaking image at the far end of the corridor, a little girl who holds out her arms in a gesture which is half self-presentation, half helpless shrug. Well, you have to see it.

Andrew Graham-Dixon is away

(Photographs omitted)