New Zealand-born Fox is funny, frank and full of insights, and she's at the Melbourne International Film Festival to share them in a masterclass on August 7. She'll be appearing with director Grant Scicluna​, director of a new Australian film Downriver which has its world premiere at MIFF. She plays the mother of a young man who has just been released from jail and is drawn to revisit the past and the mystery of his crime.  Scicluna can attest to Fox's appetite for variety; he was struck, he says, by how many options she gave him in every take.

Fox's career was launched in 1990 with Jane Campion's An Angel At My Table; she was in Shallow Grave (1995), alongside Ewan McGregor, and won the best actress award at Berlin for her role in Patrice Chereau​'s Intimacy. Later this year, she will be seen in Holding The Man and The Dressmaker, two much-anticipated Australian features.

She's given masterclasses at a range of film festivals, and she also likes to work with writers, directors and producers to teach them about actors. If there is one thing she wants to impress on them, she says, it is this: "You can't know or control the outcome. That's the hardest one, I think, for lots of new directors, writers and producers even to comprehend. They feel that they know what they want from a scene, but what they don't realise is that they're never going to get it. They can get something much better and much richer, but they can never get what they want".

Fox knows what it's like to want to be in control, it's part of her nature. But it's not part of acting. As a performer, she says, "You're relinquishing, all the time – your emotions, your memories, your experiences."  And if she has a standard form of preparation, it's involves letting go. "I have this beautiful daybed in my house, with a very inspiring painting" – by British artist Akash Bhatt​ – "and when I'm working, I spend a lot of time lying on it, just reading whatever little bits might help, and then sort of drifting, not concretely thinking about stuff, just allowing connections to come through. It's like dreaming, drifting, I don't hammer away at it."

Change is always possible and you can learn things in surprising ways, she says. Fox  remembers working with Danny Boyle on Shallow Grave, and before that on a TV series he directed called Mr Wroe's Virgins. "There was a scene under a rain machine, and I did a take and begged him to let me do it again, and on the second one I thought, yes, I've nailed it." Boyle disagreed, she says, and he made her sit and watch the two takes. "And that's when I cottoned on to the idea that I don't have to feel it, it's the audience that has to, it's not me."

With Chereau, she says, "I remember him asking me what I was afraid of, and at that time feeling that I had no fear.  The whole relationship between directors and actors was all about trust and love, there has to be love, and then you can achieve anything."

Ten years ago, she appeared in a play directed by Luc Bondy called Cruel And Tender, a reworking by Martin Crimp of Sophocles' Women Of Trachis. "He taught me about the details, and it really changed everything from that point for how I step on stage. Instead of getting myself into the headspace of where the character needs to be. I enter the take, or step on stage, exactly where I am."

One of the most difficult experiences for an actor, she says, is being part of a work that you are convinced deserves a wider audience. One example is the TV series Cloudstreet, another is Patrick's Day a 2014 Irish movie she's keen to spread the word about: "a brutal film about love and memory and the manipulation of memory". She plays the interfering mother of a schizophrenic son; it's an intense, harrowing and visually striking film, and she's passionate about it.  "What's soul destroying and painful about Patrick's Day is that it's not getting out there in the world."

For her next project, she goes to New Zealand for a film based on The Rehearsal, the debut novel by Man Booker Prizewinner Eleanor Catton. It has got her thinking, she says, about art and its powers, and the challenge of "how to express, in a creative way, truths that people can recognise from their own experience and be comforted by, knowing that they're not alone". It's a capacity she recognised early in her career, she says. "I was lucky, because that was the essence of what An Angel At My Table was. And I still have people coming to me and saying how it affected their lives and how they carried it with them."

Kerry Fox: Acting Masterclass is at ACMI at noon on August 7.
Downriver screens on August 7 (Forum), 12 and 16 (Kino), 14 (Hoyts).

The Age is a media partner of MIFF.