Reese Witherspoon wears heels in "every frame" of her latest movie after discovering what men find sexy.

The actress appears alongside Chris Pine and Tom Hardy in This Means War, which was directed by McG. The three men spent a lot of time explaining what their sex find attractive in females, which Reese tried to bring to her character of Lauren.

"I learned a lot, like they don't like flats," she laughed. "Every time I wore flat shoes they'd be like, That's not sexy,' and I have maybe 15 pairs of flats? They're like, Sorry, that's just not going to work.' So I literally, in every frame of the movie, I have heels on. Even the parts when I only had my underwear on, I still have my heels on!"

Although Reese took her work colleagues' opinions on board, she doesn't think they are completely right.

She's previously claimed having a good sense of humour is vital in a relationship and she stands by that. Reese also finds it attractive when people have something to say about the big issues in life.

"There [are] a lot of different ways to sort of get attention in this life and I think a lot of women sort of immediately get a lot of attention - especially young women - for how they look in a bathing suit or how they look sexy on the cover of a magazine," she told Access Hollywood.

"But to me, what's really appealing about a woman is her sense of humour, being able to laugh at yourself, intelligence, your opinion about things that are going on in the world.

"That's what to me makes a woman beautiful and interesting. I think it's more important to be interesting and endlessly curious than anything else."

In This Means War, Chris and Tom portray two CIA operatives who realise they are both dating Reese's character.