Big interview: The Conjuring

There's a particularly terrifying scene in The Conjuring in which a character called Carolyn Perron finds three claw-like grazes on her body.

They're not the result of an over-zealous scratch – they've been mysteriously etched onto her skin by a suspected demonic presence who leaves the marks on house guests to register its disapproval.

That would be scary enough to watch on screen but the film's leading lady, Vera Farmiga, found similar marks on her own body before the cameras had even started rolling.

"That's my thigh," says the actress, showing me a photo of the marking captured on her mobile phone. "I had a bruise on my leg, and I do bruise easily, but not in claws," she adds. In the film, Farmiga, 39, plays Lorraine Warren who, along with her husband Ed, works as a paranormal investigator.

The plot is based on a true story from the early 1970s involving the Perron family who had moved to a deserted old farmhouse in Harrisville, Rhode Island, where they found themselves the subject of some ghastly goings-on, including phantom noises, creaking doors and mysterious figures.

The story captured the interest of Farmiga, who played psychiatrist Dr Madolyn Madden in Martin Scorsese's 2006 hit crime thriller The Departed. She even met the real Lorraine, who's now in her 80s.

She immersed herself in research on the internet beforehand though, and that's when another freaky mystery occurred – marks, similar to her strange bruises, also appeared on her computer screen.

"I'd just done hours of research about Lorraine and I opened my computer and there were the same scratches across my screen," she recalls. "I don't know how to explain it. I do know I hadn't dropped the computer, my children hadn't stepped on it, so I gingerly closed it, put it away and then my brain went berserk."

Some people would be thoroughly spooked but Farmiga, who starred in The Boy In The Striped Pyjamas, is philosophical.

"If I do feel fear, I have a way to push it away," she says. "I have the confidence, love of God and the utensils, so there's no room in my life for negativity."

That said, she admits she didn't dare read the scripts at home. "I read it in fits and spurts, because it brought on overwhelming feelings: terror, awe, shock," she recalls. "I didn't ever want to read the script at home. I figured the safest thing for me would be to read it somewhere else during the day."

She's no stranger to creepy stories, having starred in 2009's mystery thriller Orphan and the TV series Bates Motel, a prequel to Alfred Hitchcock's Psycho.

She also directed Higher Ground, a weighty drama about faith – an issue she was interested to revisit in The Conjuring, as Lorraine is a devout Catholic.

The real-life Ed died in 2006. The couple also worked on the Amityville hauntings, which inspired the ghost film series of the same name.

While the husband and wife team are at the centre of The Conjuring, horror is always lurking – it's terrifying in parts!

Luckily for Farmiga, she was able to have a change from 'things that go bump in the night' afterwards.

The actress – who is the eldest of seven siblings, her youngest sister being Bling Ring actress Taissa Farmiga – recently worked on comedy drama The Judge, due to be released in 2014, which sees Robert Downey Jr play a lawyer.