In Glorious Technicolor: A Century of Film and How it Has Shaped Us, By Francine Stock with Stephen Hughes

In 1916, US cinemas received instruction on the purpose of film: "I stir the blood, I quicken the pulse, I encourage the imagination, I stimulate the young, I comfort and I solace the old and sorrowing...I am the motion picture."

At this fundamental level, even Transformers 2 fulfils part of that brief, but how and why do movies affect audiences, and what do they tell us about the times in which they're made? It's surprising how few good books there are about the relationship between watchers and the watched.

Stock's approach is to examine three key films from each decade, picking them apart to understand their influence, and adding examples along the way. The title could also be reversed to point out how our hopes and fears have shaped film. Choices at the outset include The Cabinet of Dr Caligari, The General and Scarface, where we see that the need for artifice and the desire to emulate continually cross each other. When movies aren't scanning the real world for copycat behaviour, the exact opposite is happening.

If Spellbound reflected an increased interest in the subconscious and Invasion of the Body Snatchers unveiled our fear of losing our identity, are films just "the dreams we dream of having"? Do directors knowingly provoke their audiences, or do we believe Body Snatchers director Don Siegel when he shakes off any suggestion that his movie was intended as an allegory?

With the Sixties came empowerment via the freewheeling youthful energy of Bande à Part, but the disillusioned Seventies are represented by Carrie and Annie Hall, not The Parallax View or Three Days of the Condor. Stock makes surprisingly little reference to the impact of Easy Rider, dismissing it as a failure (although my entire class watched it repeatedly and obsessively, allowing it to shape their world view). Film studies let you build an intelligent argument for virtually any film to represent its era, but at some point personal taste kicks in with the recognition that the most unlikely films may have gained access to your heart.

At this point it becomes hard to tell what effect the author is striving for. If the intention is to show that cinema's practitioners have manipulated us with ever-changing agendas, the chronology is far from exhaustive, so perhaps this is best approached as a personal history peppered with pleasurable asides. I liked the fact that Kabul marriage celebrations chose the Titanic ship to grace wedding cakes.

By the time we reach the Nineties, with globalisation requiring film to broaden its horizons and new levels of introspection turning us inwards, the brief has broadened to review recent cinema history, including 3D and its failure to understand how depth perception works. A look at Avatar crystallises Stock's theme; film continues to explore how the unconscious works, so that even a terrible movie may accidentally enlighten.

Christopher Fowler is working on a book called Film Freak, a sequel-of-sorts to his acclaimed childhood memoir, Paperboy (Bantam, £7.99)