Despite huge investments, user interfaces for interactive television remain so poor that frustrated viewers are suffering from "mad couch disease".

A study of interactive TV in Britain, the US and France concludes that viewers are afflicted with "viewer vertigo, remote control anxiety, set-top boxing and perpetual channel surfing".

According to consultant Ms Shelley Taylor, whose company produced the report, StayTuned2, "current iTV initiatives risk repeating the early and costly mistakes of website design. Just as e-commerce sites jettisoned all traditional merchandising wisdom, ignored consumer needs and marched blindly in the direction of false profits, iTV companies are focusing on technology rather than creating a compelling viewing experience."

The first problem for viewers is finding which programmes offer an interactive element. Viewers are confronted with an "obstacle course", says the report, because such content is not clearly flagged by broadcasters. British iTV is the worst in this regard.

Interactive TV developers have also failed miserably at making television a friendly medium for viewing Web or other interactive content, says the report. And, television commerce, or "T-commerce", is, by and large, a hideous experience for viewers who might want to purchase something via their TV.

"Most iTV shops bar the door to transactions to all but the most tenacious shoppers by failing to mimic even the most basic bricks-and-mortar shopping conventions," says the report.

Many iTV companies are following a path better suited to passive viewing, said Ms Taylor. However, iTV is very poor at accommodating several viewers.

Community viewing is nearly impossible due to the lack of onscreen cues, meaning selections made by the person in the room who controls the remote are largely invisible to other viewers, causing them to become hopelessly lost, the report says.

According to the report, the best iTV providers by country are: UltiimateTV on DirecTV (US); Sky (UK); and TPS (France).

Despite its lacklustre state, Ms Taylor believes iTV has enormous potential. Basic enhancements should include e-mail, chat and SMS services, the report says.