Revelations in the dark: Stars reveal the film that changed their life

From the Lumière brothers to Star Wars and beyond, cinema has long had the capacity to shape imaginations. Geoffrey Macnab assesses its transformative power

There is a very famous moment in Preston Sturges's film Sullivan's Travels (1941.) A big-shot Hollywood director (Joel McCrea) who wants to discover "real life" has ended up a convict on a chain gang in the Deep South. His ambition is to make serious, socially relevant movies. However, in captivity, when he watches a Mickey Mouse film with the other inmates, he begins to roar with laughter. This is his moment of revelation – the movie that changes his life and his approach to filmmaking. He realises his vocation is to entertain audiences, not to preach at them.

Can films really have such an immediate impact? "It is a rather simplistic and all too tidy journalistic idea that a film is the only film that is an epiphany. It's a nonsense really. One goes through an endless cycle of cumulative experience," the British director Mike Leigh told me when I was preparing the recent book Screen Epiphanies. Nonetheless, there are many, many instances of films – and of moments in films – having an overwhelming effect on cinemagoers.

This week, in Cannes, an unheralded Danish documentary called Armadillo had a very immediate impact on audiences. The film portrays the experiences of Danish soldiers in Afghanistan and exposes an incident in which the soldiers may have behaved "inappropriately" in a combat situation. A low-budget film that few had heard of has now provoked a furious debate among Danish politicians – and it could cause Danish foreign policy to be changed. "Prior to this film, we [Danes] have had some virgin belief that we never killed anybody. We thought we were there [in Afghanistan] to give out candy for kids and build schools," the producer Ronnie Fridthjof commented.

As Armadillo's impact underlines, films can indeed change lives. During the early part of the Second World War, William Wyler's Mrs Miniver, a stirring melodrama about a British home-counties housewife, was credited by some with swaying American public opinion in favour of the war.

The impact, though, was largely attributable to the films' topicality. This is very different from films having a seismic effect on individuals.

There are different ages at which cinemagoers are most impressionable. When they're very young, the experience of seeing a film on a big screen can be both exciting and overwhelming. Children have the same innocence as those early viewers of Lumière brothers shorts, who used to duck out of the way when a train on screen came careering towards them. They're drawn to the exotic: the otherworldly universes of films such as The Wizard of Oz or Powell and Pressburger's A Matter of Life and Death. It's the same instinct that pulls so many toward Star Wars and other galactic franchises they can lose themselves in.

The cinemagoing experience itself is often what makes such an impression on them. The British director Terence Davies has given Proustian accounts of his experiences as a boy growing up in Liverpool, being taken by his sisters to see Doris Day movies. He can remember precisely which seats he sat on, which route he took to reach the cinema, and the look on the face of the usherette who tore the tickets. The irony is that the films that Davies himself was later to make were the antithesis of the Day movies that so inspired him in the first place. It's a long way from the iridescent optimism of Pillow Talk or other Doris Day and Rock Hudson movies of the 1950s to the brooding family psycho- dramas of the Terence Davies Trilogy or Distant Voices, Still Lives.

Children are often susceptible to films with a raw emotional voltage – hence the numbers who cite the death of Bambi's mother or the unveiling of the runaway convict as not being Jesus in Whistle Down the Wind as key moments in their lives. (Paul McCartney credits Bambi with sparking his passion for animal rights.)

The late Anthony Minghella insisted that his later interest in filmmaking had its roots in the night when, as a young boy growing up on the Isle of Wight, he saw Josef von Sternberg's The Blue Angel on TV. This was a movie about sexual obsession and humiliation. It was exotic and confusing for the boy, who hadn't understood before that adults were capable of treating each other quite so cruelly.

As a teenager, the pastor's son Ingmar Bergman saw a film that terrified and obsessed for the rest of his life – and that laid out the themes he would explore again and again in his own work. The film was Victor Sjöström's The Phantom Carriage. Bergman watched it projected on a white sheet in a church hall. A tale about broken marriage, alcoholism, guilt and the fear of death, it was a movie in which he seemed to find his own reflection.

It is striking how many actors cite seeing Alan Parker's Bugsy Malone at a young age as an experience that changed their lives. They were seeing fellow tykes on screen. They began to think that they could emulate Jodie Foster and Scott Baio. Maybe the movie world was not so distant after all.

In adolescence and early adulthood, cinemagoers are particularly open to the transformative power of cinema. They're beginning to formulate their opinions and a particular film can sway them in one direction or another. "It is very rare to find a child or a young person who can be critical and intellectualise why they like or don't like something. Later, you start analysing what you like and what you don't like. It's late teens, I suppose – in late, late teens, you start focusing your attention more on likes and dislikes," the British producer Jeremy Thomas suggests.

Often, the films people see in their late teens define their attitudes toward cinema. They identify strongly with films that capture their own feelings of defiance and antagonism toward authority figures. Would-be teen rebels relish movies about teen rebels. Steve McQueen, James Dean in Rebel without a Cause, Marlon Brando in On the Waterfront or The Wild One – these are the titles that are often mentioned.

Films can change lives in a damaging way. One thinks of John Hinckley's obsession with Taxi Driver, which was cited as a key factor in his attempt to assassinate Ronald Reagan, or of fans who stalk movie stars after seeing them in the same film again and again.

On a far more positive note are the films that inspire viewers to pursue unlikely dreams. The success of fictional movie characters in overcoming adversity (climbing mountains, beating disease etc.) gives viewers the confidence to do the same. Then there are the musicals that so exhilarate viewers that they think they can do anything. There are also films that change lives in a more low-key way. Would-be directors spot the joints in a movie and begin to work out how it was constructed. They realise that they are capable of doing the same themselves. That was the case for Paul Schrader as a young film reviewer watching Robert Bresson's Pickpocket.

"I saw a kind of film that I not only liked but I knew how to make – I knew I could make," he later said. "This was a kind of an existential character drama about a single character who is in every scene and who drifts around, peeping in on the world, who is a solitary man, who lives in a spare room and who is slowly undergoing a transformation." Every Schrader film has been made from the same template.

Many Brits and Europeans talk about Hollywood changing their lives. To those growing up in austerity, US movies held out the promise of Technicolor, sex, the promise of plenty. They offered a dream to aspire toward.

Of course, the most obvious way in which film transforms lives is that it hooks viewers. They become hooked on the medium itself. As Martin Scorsese and others have observed, film is like a narcotic. For those who are hooked, it is not an alternative to reality. It eventually becomes reality itself.

FILMCLUB the nationwide after-school club which gives children free access to thousands of films, is launching an ambitious 'Film Journeys' season. The aim is to educate schoolchildren about the world through film. For more information on FILMCLUB and how to sign up for an induction in your area please visit: www.filmclub.org and click on "WANT TO SET UP A FILMCLUB?"