The lights above the empty gallery flickered, went out for a while, then irritatingly flickered again. It seemed to be a graphic example of the underfunding of museums and the ongoing problems with the Tate Gallery's electrics.

But a dodgy illumination is among the entries for this year's Turner Prize. They will be exhibited from today to those willing to pay a £3 admission charge to view an example of art that really can be seen at home.

But should even the most devoted students of contemporary art begin to wonder whether the Turner Prize has at last become a parody of itself, the Tate's own communications curator, Simon Wilson, was on hand yesterday to give the official line on why the bust light bulbs (or to give them their proper title Work 227: The lights going on and off) by conceptual artist Martin Creed, 33, really was art.

In a speech which will either elevate him to a chair of art history at the Courtauld Institute or a season of stand-up at the Comedy Store, Mr Wilson said: "I think life is like that work. One minute it's on, the next minute it's off. It's emblematic of mortality. What Creed has done is really make minimal art minimal by dematerialising it – removing it from the hectic, commercialised world of capitalist culture. His installation activates the entire space."

It was not the easiest day for the Tate's communications curator, deputed by Tate director Sir Nicholas Serota to illuminate (with flickerings or not) the four Turner entries to assembled art critics and journalists. Examples of works by the four shortlisted artists will be on show at Tate Britain on London's Millbank until January.

After rhapsodising about the flickering light, Mr Wilson turned his attention to the architectural installation by Mike Nelson, 34, which was grandly titled The Cosmic Legend of the Uroboros Serpent. His work, a network of decaying corridors and an old storeroom, is meant to be indicative of the Tate's own closet.

"But I thought it was the Tate's storeroom," said an art critic who thought she had gone into the wrong room. "Why on earth is it a work of art?"

Mr Wilson was prepared: "These labyrinths relate to aspects of everyday life. They can create a sense of disorientation and mystery. When you go in there you do think you have strayed into the Tate storeroom. Nelson has combined references to the museum itself. It is a work of art because it is an imaginative reconstruction of reality."

After this, the landscape photography by Richard Billingham, 31, was remarkably uncontroversial; but lest he be thought too tame he is also exhibiting Ray in Bed, a home video featuring Billingham's alcoholic father reluctantly waking up as his wife brings him a cup of tea.

Ironically, Mr Wilson neatly side-stepped the real controversy in the exhibition – Isaac Julien's video installations. The ownership of one of them – The Long Road To Mazatlan – has been disputed in the High Court between Julien, 41, and his collaborator, the choreographer and dancer Javier de Frutos. This was a controversy the prize's organisers preferred to ignore.

Not for the first time does the shortlist for the £20,000 prize for contemporary art contains not a single painter. The prize will be presented by Madonna at a ceremony at Tate Britain on 9 December. All four artists on the shortlist are British.

Even before the exhibition opens to the public, it has already been the victim of one delicious irony. At yesterday's private view a visitor scrawled the words: "This is crap" on a dusty mirror in the "storeroom" of Nelson's exhibit. Five minutes later art was imitating life as photographers snapped the curt comments on the mirror.

They thought the comment was an "ironic reference" by the artist to his own work.

Others, who gathered outside the museum yesterday, failed to see the "irony" as they protested about the "worthless exhibits" inside.

Charles Thomson, the founder of the anti-Turner Prize group, the Stuckists, said: "It has gone beyond a joke. It's a case of the Emperor's New Clothes. But the only people who cannot see how ridiculous this whole thing is are the organisers themselves."

Janet Lee, the arts editor at Channel 4 arts, which sponsors the prize, said: "Nothing has done more than the Turner Prize to raise the profile of contemporary art. It puts modern art under a unique critical spotlight."

Shortlisted artists in previous years have included Tracey Emin in 1999 with My Bed, an unmade bed with grubby sheets, surrounded by condoms, cigarette-ends and bottles of vodka. The winner in 1998, Chris Ofili, used elephant dung mixed with paint in his paintings, and the 1995 winner, Damien Hirst, exhibited the severed remains of a cow and calf preserved in formaldehyde.

This year's ceremony at Tate Britain will depart from tradition. In the past it has been a sit-down dinner – the hottest ticket in the art world. This time the glamourous throng will have to stand until Madonna presents the prize, in an effort to make the event less exclusive and include more guests.

The jury, chaired by Sir Nicholas, includes Patricia Bickers, editor of Art Monthly, Stuart Evans, a representative of the Patrons of New Art, Robert Storr, senior curator of painting and sculpture at the Museum of Modern Art in New York, and Jonathan Watkins, director of the Ikon Gallery in Birmingham.

Given Madonna's presence, this year's prize could be the most glamourous event in its 17-year history. But glamour appears to take second place to controversy in the mind of Sir Nicholas. The reason he changed the rules so the winner would be selected from a publicly announced shortlist was recently revealed. And the logic was simple: the greater the number of controversial works the prize could exhibit, the more intense the publicity.