Big Brother contestants were watched by millions

Dr James's comments were backed up by TV presenter and columnist Vanessa Feltz, who separately accused the makers of celebrity Big Brother of making her look like "Jack Nicholson out of the Shining".

Ms Feltz took part in an "all-star" version of the reality TV show in aid of charity earlier this year and appeared to have a "breakdown" on the show.

She was also speaking in Edinburgh, and said that the show was edited to make her look mad, according to The Guardian.

Feltz said any members of the public who thought they had nothing to lose by entering The Big Brother house were misguided.

Feltz was delighted to leave Celebrity Big Brother

"You lose your privacy, your past, your future," she said.

"They go in and they subscribe to this utterly specious notion that fame is entirely desirable."

Channel 4's Big Brother does use psychologists to help choose suitable contestants and also offer "aftercare" when the show has finished.

But Dr James had spoken to contestants like Allan Bridges, who featured in Channel 4's Shipwrecked, who thought the show would lead to a TV career.

'Vulnerable'

"The clinical psychologist in me can't help worrying about Allan Bridges and the dozens of other people in reality television programmes that might actually be damaged by taking part," James said.

The clinical psychologist is best known for making Peter Mandelson cry during an interview for television.

He is the author of Juvenile Violence in a Winner-Loser Culture and Britain on the Couch - Why We're Unhappier Compared With 1950 Despite Being Richer.

Narinder Kaur: Found it "humiliating" outside Big Brother house

James believes that a proper scientific study could help out broadcasters who cannot be expected to act as social workers.

"The results of a study could be used to screen our vulnerable people," he said.

And he added: "It's not just namby pamby psychobabble to say that the broadcasting industry should fund this study."

BBC One controller Lorraine Heggessey agreed that many participants did not realise the impact of what they say on camera when it was screened on TV.

Her words were borne out by Narinder Kaur, who appeared in this year's Big Brother series, and is hoping to begin a career as a radio DJ.

"I came away from this experience thinking 'Oh my God, did I really say that?'" she said.

"I've found it more humiliating coming out, not being in there."