Michael Keaton takes flight in Birdman at Venice

Keaton (second from right) with director Alejandro Inarritu (middle) and his Birdman co-stars in Venice

Michael Keaton says playing superhero Batman has had "a profound effect" on his life as his latest movie, Birdman, opens this year's Venice Film Festival.

Birdman, or The Unexpected Virtue of Ignorance, by Alejandro Inarritu, the Mexican director of Babel, sees 62-year-old Michael Keaton appear alongside Edward Norton, Emma Stone, Naomi Watts and Britain's Andrea Riseborough.

Keaton plays Riggan Thompson, an actor who is attempting to breathe life into his moribund career by directing and starring in a Broadway play, an adaptation of Raymond Carver's short story collection What We Talk About When We Talk About Love.

Both Keaton and Inarritu said there was an "awareness" Keaton could bring to the role "like no one else", thanks to his two appearances as Batman under the direction of Tim Burton.

"Does Batman follow me around?" Keaton mused. "Certainly it had an effect, because it was so groundbreaking. Tim's vision has been copied and changed, but it was the first one.

"I was part of that and proudly so, and I totally embrace it. I think the big deal was the fact it was the first, and it did change my life.

"When something breaks on an international level, that's a whole new deal, and although I was a known actor, it was primarily in the USA. I think that was the first thing that changed, and the reality is, that is a big thing.

"I'm okay with it, and I'd like to say that Batman doesn't follow me around," the actor continued. "Nothing follows me around.

"Perhaps a part that I wasn't very good in follows me sometimes, and even that doesn't go on for very long. I would like to say, though, that we all have a Birdman in our life. We just can't allow him to have the driving seat in our life."

As opening night looms, Riggan attempts to make a success of his play but is hampered by problems with his ex-wife, his daughter (played by Stone) and an out-of-control leading actor (played by Norton).

Meanwhile, Riggan's superhero alter-ego Birdman appears to him and whispers self-doubt into his ear. He is, said Norton, "the personification of fear".

Edward Norton (right) plays the temperamental star of Keaton's stage production

"I think Alejandro's vision is very much about a person hitting a certain time in life, when all of us start to think about what we've done, what we hope to do, and have we gone too far away from what we wished to be when we were younger.

"It's as true for a doctor or a lawyer as an actor. It's just the melodrama is heightened by setting it in a theatre. For all its experimental creativity, the film is as much about hitting your midlife crisis as it is about art."

Inarritu - until now the maker of such hard-hitting dramas as Babel, 21 Grams and Biutiful - said Birdman was a "switch in genre" for him. "It was a challenge to make a comedy," the 51-year-old went on.

"It really scared me. But I always say, after the age of 40, if you're not doing something that frightens you, it's pointless.

Emma Stone, who plays Keaton's daughter, says everyone has "some kind of Birdman in their life"

"I see Riggan as a Don Quixote. There is an innocence to him, but like many people, he has confused love with admiration, and he has to realise the irrelevance of this second quality.

"There's a modern definition of accomplishment - people want to be famous immediately, not from a body of work developed over years.

"In one second, people have 800,000 likes or followers, and for some that is achievement in itself. But it's delusional.

"For Riggan's tortured ego, the line between reality and illusion is thin and often not there at all. Birdman is a super-ego, and his shadow is a constant, nagging companion. It's always there, whether he likes it or not."

Emma Stone, recently seen as the title character's girlfriend in The Amazing Spider-Man and its sequel, said she was "glad that finally everyone's admitting they have some kind of Birdman in their life".

"The film taps into something true, whether it's your ego, or just your critical inner voice telling you you're a failure no matter what you do. For some it's a louder voice than others."

Amy Ryan (left) plays Keaton's character's long-suffering ex-wife

Birdman offers a highly-strung portrayal of the Broadway theatre scene. Yet Stone said the film had not made her wary of making her own Broadway debut in Cabaret next year.

"No, it makes me want to do more," she told reporters in Venice. "There's something so visceral about theatre, about living it every night. It's incredible".

Reviews of Birdman so far have been positive. The London Evening Standard called it "an expertly delivered black comedy about showbiz and celebrity" and said that Keaton had "never been better".

Trade magazine Variety, meanwhile, called his performance "the comeback of the century", praise that is echoed by Alejandro Inarritu himself.

"One thing was very clear about [Michael], and that was his self-assurance," said the director. "He may know all about the fragile ego of acting, but I have never worked with anyone who is so secure in himself.

"He doesn't have to empower anyone else to tell him who he is, he just has a clear vision of himself. He may be the only one of all of us without a Birdman in his life."

The Venice Film Festival runs until 6 September. Birdman is out in the UK on 2 January 2015.