UPDATE 1-Vince Vaughn victorious with 'Couples Retreat'

* “Couples Retreat” earns $35.3 million

* Critics hated the Vince Vaughn comedy

* “Paranormal Activity” scares up big business (Updates with sales of “Paranormal Activity”)

LOS ANGELES, Oct 11 (Reuters) - The critically maligned Vince Vaughn comedy “Couples Retreat” easily took the top spot at the weekend box office in North America on Sunday, helped by the absence of any other new releases.

The film earned $35.3 million during the three days beginning on Friday, confounding industry forecasts of an opening in the $20 million range.

Paradoxically, the Universal Pictures project was released four days after studio chiefs David Linde and Marc Shmuger were ousted from the General Electric Co GE.N unit in the wake of a dismal summer at the box office.

Vaughn stars as one half of a couple who join three other couples on a tropical island for some counseling. He co-wrote the script with his “Swingers” co-star Jon Favreau, who also appears, alongside the likes of Kristin Davis and Jason Bateman.

It marks Vaughn’s best opening since “The Break-Up” launched with $39 million in 2006. But critics overwhelmingly trashed the picture. Time magazine said it was “offensive.” USA Today said it was “tedious.”

Universal said women accounted for 61 percent of the audience, while 56 percent of the audience was aged 30 and older.

One other film arguably made a bigger splash, a low-budget horror flick driven almost exclusively by fan-driven word-of-mouth. Paramount Pictures’ “Paranormal Activity” jumped 15 places to No. 5 after earning $7.1 million in just 160 theaters. The top three films, by contrast, were each in about 3,000 theaters.

For the past two weekends, the scary-house film played to sellout crowds at midnight-only screenings in a handful of markets determined by online balloting.

Taking a page from the playbook of the underground smash 1999's "The Blair Witch Project," the Viacom Inc VIAb.N unit is letting the fans do the marketing through such social-networking sites as Twitter. Its own marketing costs have been minimal.

“Most people found out about this through the recommendation of a friend,” said Rob Moore, the studio’s vice chairman.

Paramount bought the $15,000 movie last year at the Slamdance Film Festival, an indie rival of the concurrent Sundance festival in Utah.

Last weekend's top film, "Zombieland," slipped to No. 2 with $15 million, while past two-time champ "Cloudy with a Chance of Meatballs" was down one to No. 3 with $12 million. The respective totals for the Columbia Pictures releases stand at $47.8 million and $96.3 million. Columbia is a unit of Sony Corp 6758.TSNE.N.

Walt Disney Co's DIS.N 3D reissue of the hit Pixar cartoons "Toy Story" and "Toy Story 2" was also down one, to No. 4, with $7.7 million; its 10-day tally rose to $22.7 million.

Editing by Eric Walsh