Adam Arkin — American Actor born on August 19, 1956,

Adam Arkin is an American television, film and stage actor and director. He played the role of Aaron Shutt on Chicago Hope. He has been nominated for numerous awards, including a Tony (Best Actor, 1991, I Hate Hamlet) as well as 3 primetime Emmys, 4 SAG Awards (Ensemble, Chicago Hope), and a DGA Award (My Louisiana Sky). In 2002, Arkin won a Daytime Emmy for Outstanding Directing in a Children's Special for My Louisiana Sky. He is also one of the three actors to portray Dale "The Whale" Biederbeck on Monk. Between 2007 and 2009, he starred in the NBC drama Life. In 2009, he portrayed villain Ethan Zobelle, a white separatist gang leader, on the FX original series Sons of Anarchy. He is the son of Oscar winning actor Alan Arkin... (wikipedia)

We all look to have transcendent experiences that lift us out of the everyday, and fear is a good one. But, I think it's the same reason why people want to laugh their heads off.
I think in the case of horror, it's a chance to confront a lot of your worse fears and those fears usually have to do, ironically, with powerlessness and isolation.
I think that was the case here. We just wanted it to be good for everybody.
To confront those fears, in a controlled environment, where there's 300 people around you going through the same thing, it's this weird sort of yin and yang.
The idea of it becomes a little freaky if you're dealing with someone who has trouble differentiating between fantasy and reality, but that's a concern no matter what kind of movie you're dealing with.