Jon Ronson

The author and film-maker on George Clooney, Ian Paisley and psychopaths in the room

Part of Jon Ronson's success as a writer and film-maker, documenting the exploits of the world's weirdest people, must come from the fact that he looks and sounds so innocuous. Small in stature, with youthful spiky hair, a washed-out t-shirt and little round glasses, he has the manner of a charming but slightly bewildered schoolboy.

As he walks, or rather shambles, on to the stage of the Black Box in Belfast clutching his latest book – The Psychopath Test: a Journey Through the Madness Industry – and a bottle of Peroni, you can see how he would lull his subjects into a false sense of security.

Not that Ronson is ruthless or exploitative in his methods. He's a pleasant sceptic, a wry observer rather than a ranting polemicist, which is refreshing these days when ranting polemicists are two a penny. But you would be a fool to underestimate him.

The other thing you need to know about Ronson is that he is a very funny man. His self-deprecating anecdotes get big laughs from the audience, right from the start. He talks about the DSM, the bible of mental health disorders: 374 pages long, it contains 886 possible maladies. 'I realised that I have 12 of them,' he quips, deadpan. 'Malingering, generalised anxiety disorder…'

I can believe he's a tense man. He constantly fiddles and twiddles, with his beer bottle, with his hair, never sitting still for a moment. But his new book is not about low-level neuroses like anxiety.

Ronson set out to discover the nature of real madness. He met the likes of Tony, the Broadmoor inmate who insists he faked insanity to get off with a lighter sentence, but who cannot now convince the authorities he is sane, and the influential psychologist, Robert Hare, who developed the standard clinical test for psychopathy, and who believes that many important CEOs and politicians are themselves psychopaths.

In fact, it turns out that psychopaths are surprisingly common. Ronson estimates that, statistically, there are at least two in the room during his performance. There might even be more, says Ronson. It depends on whether psychopaths, who are notoriously self-obsessed, like going to talks about psychopaths.

This evening is not all about craziness though. Questions from the audience prompt a range of thoughtful observations and bizarre stories from Ronson. Asked about his interest in extremists of various kinds, he says that 'a good way to learn about our world is to stand at the edges, looking in'.

There's a fair bit of interest in what Ronson thought of George Clooney, who appeared in the film adaptation of Ronson's book, The Men who Stare at Goats. 'He was like an awesome butterfly floating into my life and then disappearing again,' Ronson says. He wasn't impressed with Hollywood though, finding it 'brittle, cold, and full of schoolyard machismo'.

One of Ronson's best received anecdotes is about Ian Paisley, who he once accompanied on a missionary trip to Cameroon. Paisley continually referred to Ronson as 'The Jew' or 'my circumcised friend'.

Ronson describes receiving a call from his wife, then pregnant with their son, to say that it was possible the child might have Down's syndrome. By his own account, the habitually anxious Ronson 'freaked out', and sought out Paisley for some spiritual advice.

However, he never got further than tentatively asking, 'Er, Dr Paisley…?' The big man boomed, 'I'm busy, not now.' And that was the end of that encounter.

Ronson is a practised raconteur, who keeps the Out To Lunch Festival audience effortlessly entertained from start to finish. If I have one criticism, it is that we hear so little of him reading from his own books. But that's a small complaint in an evening of wit, hilarity and insight.

Visit the Out To Lunch website for forthcoming festival events.