Actress Leighton Meester stars in the upcoming thriller "The Roommate."

Q: After watching yourself in this movie, what kind of an impact did playing Rebecca have on you?

A: This movie is strange for me because I feel that I have a bit of amnesia about it. I can’t say it wasn’t fun. It was, but it was also intense, I think for everyone. It was really quite a time for me.

I tried to share something in common with her or try to understand her motives and relate to her in some way. It was extremely difficult for me to do that with her starting off because of how she unravels.

From the outside she seems like a really good friend, good person. She’s understanding, she’s artistic, she’s trustworthy but then eventually she just completely loses that. So I mean during filming, I did my best to maintain and I was really lucky because all I had to do was work on this movie everyday. I didn’t have many other obligations at the time so I got to be really involved and focused, which really was a pleasure.

Some of the things I had to do were really disturbing for me particularly a scene involving a kitchen. It was an intense experience.

Q: What was it like specifically trying to play the villain?

A: [When I saw the movie] I was genuinely scared at points. But it is sort of funny I’m what’s scary in the movie. I’m really proud of it and how it turned out. It’s definitely a ride. It’s got a lot of levels. It’s sexy and exciting and scary and jarring and disturbing.

Filming it, it was all of that too, it was all those things. I can’t say that I wasn’t at all affected by it. I think it stays with you a bit if you’re terrorizing people all day. Overall it’s exciting.

Q: How did you prepare for your role in “The Roommate”? It’s so psychological; did you do any research into that?

A: I had the chance to speak with different psychiatrists about the disorder and they had all kinds of information. I think it’s a very interesting subject: a woman who sort of loses a grip on reality.

The psychiatrists I spoke to I think were the most helpful. They would describe in gross detail different cases that they’ve worked on defending their patients who had been convicted of a crime. I’ll spare you those details, but it’s definitely dark in the mind of someone who’s living like this.

It was interesting for me because I have, what I believe is, a firm grip on reality. I’m weird and crazy like anybody else, but this person, she really doesn’t have control of her mind whatsoever and the decisions she makes are not based on rational thinking. So it’s interesting and somewhat uncomfortable at the same time.