Peter Sarsgaard only learned after he’d filmed “Memory” that it was his co-star Jessica Chastain who suggested him for the role of Saul, a man suffering from dementia who embarks on a relationship

with Chastain’s social worker. It was a smart call; when the Michel Franco film premiered at this year’s Venice Film Festival, Sars- gaard took home the Volpi Cup for best actor. “Memory” hits the U.S. in a limited release Dec. 22 before going wide Jan. 5.

This movie deals with dramatic events, but it’s not maudlin — it’s even funny in places.

I really wanted to make this a different portrayal. Dementia is his condition, but it’s not his character. This is a guy who has a limited amount of time in his life, and he knows it. But he’s still quite viable throughout the movie. I liked that he was a pos- itive person; he wasn’t just going to be some sad character in his bed at home. There’s a group in New York called Reimagining Dementia — I didn’t work with them directly, but I worked with a doctor associated with them. And it’s about just that — having a different point of view.

I heard this film was shot in a unique way.

It was unusual. Most scenes are done in one shot, these long, unbroken takes. And some were only shot once. Michel was editing in the same building where we did a lot of shooting, and he could literally go and watch it and then come back and tell us if we needed to adjust it or do it again. It gave us a real continuity.

Maybe because both you and Jessica have a stage background, you were comfortable with letting those scenes play out.

We control our own timing — no one can make it longer or shorter. So that’s a responsibility we carry. On the other hand, Michel says the thing that he worries about most is boring the audience. It’s a very real concern for him. Sometimes he would just say, “It’s not worth watching.” He’s very, very honest.

And you appreciate that honesty?

I do. There’s a tendency for more people to act as if everything is OK, even when it’s not. You don’t need to sugarcoat it for me. I think of a director like Lone Scherfig, who I worked with on “An Educa- tion.” She’s Danish, and so maybe it’s just her tone. But she would say, “Peter, that last take was very bad.” Then in the exact same voice she’d say, “Peter, that was very good.”

I have a friend with a similar cadence; people think she’s being mean, but it’s just her way of speaking.

And mean is OK! If the only way someone can say the truth to me is by being an ass- hole, at least I’m getting the truth. There are very few directors I’ve worked with that I wouldn’t work with again. Most of the people I’ve worked with have been worth knowing and had interesting things to share.

You’ve played such a wide variety of roles. What do people most want to talk to you about?

It’s always different. Frequently it’s one that is more uncommon. For a while, there was a very spe- cific demographic that would come up to talk about “The Dying Gaul.” Sometimes it was “Empire” or “Orphan.” It’s interesting — I can sort of guess what film it will be when I see someone coming. The one thing I don’t like that I only get occasionally is “What movie do I know you from?”

Things you didn’t know about Peter Sarsgaard

Hometown: St. Clair County, Ill.

Stage might: He’s appeared in such plays as “Hamlet,” “Uncle Vanya” and “Burn This”

Series on tap: He has a rolein the AppleTV+ limited series “Presumed Innocent” opposite his brother-in-law, Jake Gyllenhaal