

Harry Dean Stanton and Emilio Estevez in Repo Man.

It was January 1985. For the wider world, the year ahead would offer the ascension of Mikhail Gorbachev, the pro debut of Mike Tyson and the phasing out of red telephone boxes - but in a frost-bitten corner of west London, my scraggy existence was about to undergo a far more seismic change. I was 12, the strange bud of adolescence preparing to bloom - and at the Electric Cinema on Portobello Road (this being the time before braying men in rugby shirts took over Notting Hill), a sackably lax usher allowed my underage self into the film that would, moments later, change my life: Alex Cox's Repo Man.

I imagine most people reading this will have their own equivalent - the film that first rocked their world, blew their tiny minds, introduced them to the all-consuming marvel of cinema. But Repo Man was mine. Squinting through a veil of cigarette smoke, all but pinned back in my seat as Iggy Pop's theme tune blasted tinnily from the Electric's speakers, I watched agape as the frantic title sequence of a radiation-green road map of the route from Los Alamos to California gave way to the opening scene of Frank J Parnell's stuttering drive across the desert: the first sardonic note of the film's account of a stolen Chevy Malibu with a secret in its trunk and, in its way, pretty much everything else besides. And something deeply significant clicked into place for me.

Given my age at the time, the strange thing is, having watched it semi-regularly over the last two decades, I still think the film's a stone classic. Still as fuck-you funny now as then; still as prescient in its fixation with conspiracies and coincidence; still as potent in portraying an LA (and by extension a world) at once feral and beigely-corporatised. Now, as an adult, I'm still glad it was the one that got to me first. And that in itself is no minor stroke of luck. After all, at 12, most of us are nothing if not insanely pliable, our formative influences ingested haphazardly, stumbled on by chance - and as I think of it now, a vast streak of my own tastes can still be traced back to that glacial night at the Electric.

Musically, most of my subsequent teens were spent in a fug of American hardcore inspired by my love of the soundtrack ("You're a white suburban punk just like me"). But beyond that, with Cox's film inspiring me to seek out new pleasures, it became a template. From now, if a movie had an aesthetic best described as quick and dirty, or didn't quite fit with the prevailing cultural mood, if its humour was deadpan and the cast peppered with actors I'd never heard of but whose faces I'd seen a dozen times before, then, generally speaking, I was in. If there was urban paranoia involved, so much the better. And if the entire project ultimately proved commercially disastrous, then that was, and remains, the clincher.

As I say, I was lucky - not just because Repo Man remains so magnificent, but also because of the other movies of the same era whose far more questionable spell I could have fallen under. I'd like to think that at 12 I already had impeccable taste; the truth is I was every bit as malleable (if not more so) as any other pubescent spud boy - and I can't help but wonder what would have happened had I not wandered into Cox's masterpiece, but instead one of the grotesques lurking in the depths of 80s film like toxic jellyfish. What if it had been Alan Parker's ludicrous Angel Heart, or the hilarious Betty Blue? As it was, I hardly escaped the 80s unscathed (I recently found myself wondering if I should dig out my VHS of Nicolas Roeg's demented Track 29 - but it could have been far, far worse.

And what might I now be into as a result? A year ago, the American neuroscientist Daniel J Levitin published a book titled This Is Your Brain On Music, a hugely readable explanation of how we as humans respond to music both physically and emotionally (and how the two intertwine). In its course, Levitin discusses the way in which the music we become smitten with as adolescents remains locked in our minds to a greater degree than the music we fall for at any other time, a small part of ourselves forever replaying those same earth-shattering bars over and over.

Personally, I wonder if the same might be true of the even more immersive experience of watching films - that once we're reeled in, we're destined to have those 90 or so minutes remain a part of us forever, fruitlessly seeking another film to match them.

It certainly feels that way for me. Even now, when every visit to the mirror sparks a fresh horror at my decrepitude, a part of me still constantly hears Harry Dean Stanton railing about not wanting Christians in his car - even now, the phrase "plate of shrimp" occurs to me with metronomic frequency. So, if Levitin's theory can be applied to film-lovers as well as music fans, then I owe Alex Cox a debt of thanks - and also, perhaps, an ever bigger one to the feckless usher at the Electric in January 1985. After all, without his failure to do his job properly, I could have been writing this about Highlander.

Which films helped to form your cultural tastes, and did any movies make such a powerful early impression on you as Repo Man did on me?