In large parts of the world a light flickering on and off every few seconds in a bare room is a recognised form of torture, one the Turkish police refined to a kind of art form. But yesterday, like Carl Andre's pile of bricks, Damien Hirst's pickled sharks and Tracey Emin's unmade bed and soiled knickers, Martin Creed's The Lights Going On and Off became art itself.
But not everyone who attended the preview of the Turner prize show was prepared to accept it without a fight.
Creed's installation does exactly what is says. Every five seconds the lights go on and off in the biggest and emptiest room of this year's show at Tate Britain.
It took less than five minutes for the first visitor to crack, although it was unclear whether it was the flashing lights or the explanation from the Tate's wonderfully titled curator of communications, Simon Wilson (recently promoted from curator of interpretation), which was the greater torture.
As Wilson gallantly outlined what Creed's installation might signify - the poignance of the dying halogen glow and "the movement towards the dematerialisation of art since the sixties" - there was a barely suppressed roar of rage. A slightly dishevelled man in a leather jacket, shaking with anger, interrupted to ask, "So this is art, is it?"
Wilson said that Creed and the Turner jury, who will decide the £20,000 prize next month, certainly thought so.
"What, a light going on and off. Really!" he raged, before storming out in the direction of the Victorian Nude, the gallery's new blockbuster show.
As the usually reverential group of invited journalists and art world luminaries grew restive, a representative of the Art Fund, which rescues British masterpieces from the clutches of foreign collectors, was asked whether she might countenance saving Creed's light-switch for the nation. She wisely demurred.
There was also much muttering about whether Creed, 33, had simply recycled a five-year-old piece and why the electrician who had made it had seemingly not been credited.
Wilson had only just recovered to say how Creed's extreme minimalism was born of his wish not to fill the world with "any more clutter" when he was clobbered by another heckler. He had begun to confess how Mike Nelson's labyrinth of rooms entitled The Cosmic Legend of the Uroboros Serpent reminded him of the Tate's own storerooms when the painter Edna Weiss piped up from the back with a fresh attack.
"I thought they were the Tate's storerooms," she said. "But you tell me now they are a work of art. How could that be? So are the Tate's storerooms also a work of art then?"
Weiss had previously clashed conceptual swords with Wilson when she nominated Alberto D'Auria's ice-cream van which usually pitches up outside Tate Britain for the Turner prize.
Weiss may not have thought much of them, but Nelson's dusty corridors, windowless rooms and cubby holes haunted by their missing inhabitants - where even years of accumulated grime had been worked on to desks and doors - was the surprise crowd-pleaser, with few able to resist a broad smile.
There was a similarly warm reception for photographer Richard Billingham's two video pieces, Tony Smoking Backwards and Ray in Bed, the most moving of which showed his alcoholic father, Ray, stretched out under a flowery duvet.
The early critical favourite, however, is Isaac Julien's two films, one a collaboration with the choregrapher Javier de Frutos, which almost landed him in the courts when the two partners fought over the correct form of credit.
The prize will be presented live on Channel 4 by Madonna on December 9.
