London, Feb 2 : Keira Knightley has revealed that to get into the character for her new movie, she sat in front of a mirror to practice the facial expressions she would use during the filming of solo sex acts.

Knightley, 26, plays a young psychiatric patient Sabina Spielrein in `A Dangerous Method', who gets a sexual thrill from being spanked.

She then repeated the expressions on camera for director David Cronenberg over internet phone service Skype.

"It was a huge part of what Sabina was doing a lot of the time," the Sun quoted her as saying.

"So I asked psychoanalysts about it and they said, `Sex and anything like that is trying to release energy, trying to release pent-up emotion'.

"So I worked with that and sat in my bathroom and pulled faces at myself for about two days, trying to figure out what it was going to be.

"Then I got on Skype with David and went, `I've come up with this', or, `I've come up with this', and he went, `That one!'" she added.

The film is based on the true story of Sabina, who formed a sado-masochistic relationship with her famous shrink Carl Jung, the 20th-century Swiss psychiatrist regarded as the founder of modern psychology. (ANI)