In “Splice,” actress Sarah Polley stars as Elsa, a genetic engineer obsessed with creating new synthetic lifeforms. But that ambition leads to surprising results with the creation of Dren, a human-animal hybrid. Offscreen, Polly shares a similar drive; also an accomplished writer and director, she is gearing up to shoot her second feature, “Take This Waltz,” starring Seth Rogen and Michelle Williams. Polley spoke with Metro about both sides of her career.

Elsa is incredibly headstrong. Was it difficult to keep her sympathetic?


When anyone behaves really unethically or without humanity, it comes from a sense of a lot of pain and a lot of need, a lot of desperation. I tried to stay connected to that in some way. I don’t think she has any capacity to correct that behavior. We all know people like that — especially in the film industry.

The last film you directed came out four years ago.


Why the gap?


After I finished the press tour for “Away From Her,” I decided that I wanted to go back to acting for a year or two and see how I felt about it, just see how it had changed my approach to acting. So I took a year and a half to act, and then I took a year to think. And now I’ve been working on the script for about a year, and we start shooting soon. My favorite filmmaker is Terrence Malick, who on average makes a movie every 15 to 20 years, so I figure there’s something to that, to having time to live life before you’re speaking about it in films and to be able to absorb experience before you spew it out.

How has directing changed your approach to acting?

I went back into acting showing the directors I worked with a lot more trust. I think it’s good to be obedient to a certain extent as an actor. For me now it’s finding a balance between being really helpful as an actor to a director and also not forgetting to have any backbone at all.