That annual aberration known as the Tate Gallery's Turner Prize is with us again.

The publicity generated each year by the entries for the £20,000 prize probably adds up to more than all the exhibitions at Tate Britain, Tate Modern and the regional Tate galleries put together.

Which of course is why the director, the persuasive smoothie Sir Nicholas Serota and his willing acolytes have suckered so many otherwise sensible people into believing the submissions have artistic merit.

But this year, a wonderfully mischievous dash of piquancy has been added.

The shock-artists, brothers Jake and Dinos Chapman, who appear to hold most of their audiences in contempt, have suggested people should be intellectually means tested before being deemed suitable to view their work.

Much of it, incidentally, involves grotesque genitalia, mutilation, decapitation and other such unlovely images.

While they are not actually involved in the Turner Prize, their defiance is reflected in the attitudes of many in the contemporary art world and will no doubt be replicated by the young Turner wannabes as they get into the swing of things.

The entries are well up to the standard of previous years, which have featured such challenging delights as a flickering light, elephant dung, a pickled cow and the now infamous unmade bed surrounded by a woman's personal detritus.

As always, controversy is the name of the game. Fiona Banner's 20ft by 13ft "wordscape" (well, she would call it that, wouldn't she) is titled Arsewoman in Wonderland.

It is her lurid version, printed in shocking pink, of the plot of a pornographic film. Her explanation is classic, contemporary artspeak. In relating the pornography to her own taboos about sex she said: "It was intimate yet distant, seductive yet sometimes repulsive."

Stephen Deuchar, Tate Britain's director, used the same kind of mumbo jumbo to try to seem profound: "These are not comfortable works to view but much art is not comfortable."

Liam Gillick has suspended a ceiling of coloured Perspex panels, a bit like a fifth-rate disco.

The curators have said: "This intervention encourages visitors to engage both physically and intellectually with the manipulated environment." Don't you just love it?

Another shortlist hopeful, Brighton-based Keith Tyson, is showing a variety of drawings and objects musing, if it is not putting it too grandly, on the meaning of life.

He includes a large black monolith that hums, apparently with computer noise (the unseen brain?) - his version of that enigmatic Rodin sculpture, The Thinker.

The last finalist, Catherine Yass, uses a disorienting upside-down film to travel from the top to the bottom of Canary Wharf.

In short, Jake and Dinos Chapman have almost got it right. We do need intellectual means testing - not to ensure we are up to appreciating the works but to check why we waste our time bothering to see such trash.