LOS ANGELES, July 19 (Reuters) - Actress Vera Farmiga is now a full-fledged expert in the horror genre, but for the lead role in the film "The Conjuring" she had to study hard to see the enigmatic inner workings of a clairvoyant.

"The Conjuring," based on the true story of a paranormal investigation by demonologist and clairvoyant couple Ed and Lorraine Warren, follows a family tormented by supernatural phenomenon in their home, leading to the mother's possession by a demonic entity.

The Warrens, best known for their involvement in the "Amityville Horror" case in which a New York couple said their house was haunted by a demonic presence, are portrayed in "The Conjuring" by Patrick Wilson and Farmiga, who worked with Lorraine Warren for the making of the film.

"The most imperative thing for me was how to convey her clairvoyance and it had to do with how she perceives things, how she takes things in. What touched me about her was her incredible empathy for others, and her dedication to help others," Farmiga said.

Warner Bros' "The Conjuring" comes on the heels of a new influx of supernatural horror films waved in by the "Paranormal Activity" franchise, low-budget films that drum up big scares and revenue at the box office.

The four "Paranormal" films have earned more than $700 million at the worldwide box office since 2007 for Viacom's movie studio Paramount Pictures.

Writers Chad and Carey Hayes, who adapted the events of the Perron family's Harrisville home into a screenplay, said "The Conjuring" offered something different to the mix, telling the story from the perspectives of the investigators rather than the family suffering the events.

"There are many haunting stories where the minivan pulls up to an old house and a family goes in and eventually they end up calling the police or the professionals. We wanted to see what rocks the professionals," the Hayes brothers told reporters.

Farmiga, 39, said that while the film was rooted in horror, she viewed it as a "love story" between the Warrens, adding that "watching them together is a rare coupling."

MOTHER TO NORMAN BATES

Farmiga has found a home in horror, playing the mother of a disturbed boy in 2007's "Joshua," adopting a demon child in 2009's thriller "Orphan," exploring psychological dysfunction in A&E's series "Bates Motel," and fighting demonic possession in "The Conjuring."

The actress said the common denominator in all her horror film choices was playing a mother, which Farmiga empathized with more so after she became a mother in 2009.

"Bates Motel," which reimagines the early beginnings of "Psycho" killer Norman Bates, sees Farmiga playing Norman's highly-strung mother Norma. The actress said she was most drawn to the mental health themes running through the series.

"My compassion for Norma stems from the very essence that now I am a mother and just imagining how to deal with a child with neurological dysfunction, and a single mother at that ... what I find fascinating is not the ways she falters, but all the ways she succeeds as a mother," Farmiga said.

Farmiga, who landed a best supporting Oscar nomination in 2009 for "Up in the Air," also picked up an Emmy nomination this week for her role in "Bates Motel," and said any awards recognition was "the ultimate pat on the back."

"A nomination like that is probably the most powerful form of encouragement ... There's nothing more gratifying than positive reception and it's always really great to hear that applause and cheer," the actress said.