A couple of years ago, when I was in the closing stages of working on my last novel, Umbrella, I began casting around for a new subject for the next one. I greatly admire WG Sebald's The Emigrants, which tells the stories of six refugees from the Nazis without heavy-handedly describing the mechanics of the persecution that the regime visited on Jews, gay people and the politically suspect. Following this pattern, I conceived of writing a novel about some of the more interesting characters I had known during my two decades in the netherworld of drug addiction. I would fictionalise their stories, of course, but more importantly, I would never mention, or otherwise allude to, the reasons why these people lost jobs, experienced relationship-breakdown, moved abroad, and went to hospital or jail. Their addiction would remain a strange sort of absence, deforming the course of their lives but never emerging into the full light of day. My working rubric for the novel was "Jaws without the shark".

I began by interviewing the woman with whom I'd begun using heroin in the late 1970s – she has, thankfully, long since cleaned up from the drug, and has a sharp and incisive angle on the soft, psychic underbelly that insulated her from the sordid realities of her active addiction. At the same time, I read Peter Benchley's Jaws and watched Steven Spielberg's film adaptation of the novel. I'm not altogether sure why I did this, beyond a background suspicion that I might find something usable in this material. In the event, what struck me hard was a discrepancy between the film's script (which Benchley himself worked on), and the text of the novel.

In the film, an important scene takes place when Quint, the Ahab-like, obsessive shark-hunter, and Hooper, the cuddly marine biologist and shark expert, face off in the lurching cabin of Quint's fishing boat, the Orca. Intent on out-machismoing each other, the two engage in an unusual duel that consists of comparing their shark-inflicted scars. Quint reveals that he was a sailor on board the USS Indianapolis when it was sunk by a Japanese submarine in the last days of the second world war in the Pacific. Hooper knows all about the Indianapolis: the 900-odd shipwrecked survivors, cast adrift in the ocean between Guam and Leyte as they floated on inadequate life rafts, or paddled through the heaving swell in water-logged life jackets, were the victims of the worst shark attack ever recorded. Due to some communications snafu it took three days for rescuers to arrive, and by then there were 321 survivors – one of whom was Quint.

Yet dramatic as this incident undoubtedly was, and significant as an explanation of Quint's suicidal drive to kill the Great White that has been attacking holidaymakers on Amity Island, there is no trace of it in the original novel. I became intrigued, and read a book about the sinking of the Indianapolis – an efficient piece of reportage by Doug Stanton called In Harm's Way. From this I learned why the Indianapolis had been in that part of the Pacific theatre at that particular time: the heavy cruiser had been used to deliver the fissile material and the bomb casing of Little Boy, the atomic bomb that was dropped by the Enola Gay on Hiroshima exactly a week after the ship's sinking. This intelligence completely shifted my thinking about the novel I wanted to write. Umbrella has as its most salient theme the notion that an individual's pathology can somehow enshrine or represent the negative impact of wholesale technological change. In this text, the disease is the Parkinson's-like brain inflammation, encephalitis lethargica, and the technology is that of mechanisation, as chillingly exemplified by the production line of death that snaked across France and Belgium between 1914 and 1918.

Struck by the idea that one way to conceive of the massive shark attack was as a pre-emptive punishment, inflicted by Mother Nature on the wanton boys who'd been accessories before the fact to the poisoning of her Earth and her oceans, I began to contemplate a sequel to Umbrella that would advance the theme of pathology and technology, from the first to the second war. The illness would be the post-traumatic stress disorder suffered by a survivor of the Indianapolis, and the technology would be nuclear fission. The serendipitous stumbling on this key event, and the discrepancies in its fictive representation, also got me thinking about the relationship between film and the novel.

It's a critical commonplace to observe that, throughout the 20th century, prose fiction both responded to film and influenced the development of the new medium. The modernists of the 1900s incorporated into their texts the methodologies of montage and the camera-I point-of-view that they had garnered from film-editing technique. Indeed, it seems fair to say that the so-called stream of consciousness is itself primarily an attempt to render phenomenologically what the camera achieves simply by pointing. Our intuitive appreciation of filmic tropes is now so acute that we take it for granted that a certain camera angle is representative of an individual human perspective, while another wider or contextualised shot envisions a godlike objectivity. This sophistication wasn't shared by writers such as James Joyce, Virginia Woolf and John Dos Passos, who responded to film at a visceral, practical level – much as easel painters such as Walter Sickert responded to photography by painting over mechanically reproduced images.

Throughout the 20th century, film and the novel danced an odd fandango around one another: novelists of the calibre of William Faulkner and Aldous Huxley were drawn to Hollywood (the latter even wrote a novel in the form of a film script, "Ape and Essence"), while film itself developed new techniques in order to secure its position as the dominant narrative form. It always struck me that film was the Rome to the novel's Greece, so the continuation of the novelising project depended, in a large part, on the hegemon's dependency on this older – and arguably more revered – cultural form. Since the 1970s, in my view, film's dominance has begun to decline. The introduction of television, then the videotape and the multiplex, and the medium's ability to vertiginously suspend viewers' disbelief through special effects, have led to a loss of the collective experience of film: film still tells stories magnificently, the problem is that they're increasingly submerged in a multifarious maelstrom.

When Spielberg's Jaws plunged out of cinema screens in June 1975 there was a general understanding that this was a different kind of film experience. Viewing the film in 2014 it's difficult to understand what the fuss was about – how could anyone be taken in by that very obviously polypropylene model playing the part of a great white shark? Yet taken in we were – not only by the shark simulacrum, but by Spielberg's use of the so-called "trombone shot", also known as a retrograde zoom, or the Hitchcock shot (after its use in his Vertigo). This is the shot that we are persuaded is Chief Brody's point-of-view when he first sees that tell-tale dorsal fin: the camera simultaneously tracks down the Amity Island beach and zooms in on the shark. The overall effect is to bring the background into closer proximity while the shark attack in the middle ground remains exactly the same size. Overused in the past, the shot had become a cliche by the time Spielberg reappropriated it, but his deployment of it came at a significant moment of psycho-social change and as a result it was widely remarked upon.

The retrograde zoom strongly evokes an individual's sense of shocked realisation: objects – or events – that were formerly out of focus are brought abruptly into consciousness. But in the mid-1970s it was the future that was so precipitately looming: the future that was circling us with a potentially murderous curiosity – Jaws was simply the fishy incarnation of modernity itself. In Shark I make frequent use of the retrograde zoom – inasmuch as any filmic trope can be directly transferred to prose; but, more significantly, I make use of Spielberg's film: it's a viewing of Jaws that causes my protagonist, the maverick psychiatrist Zack Busner, to remember events that took place five years before, events that altered the course of his own life and the lives of several others.

It has long been my view that most literary fiction is written by people who read too much literary fiction for people who also read too much of it. This engenders a certain hidebound and clotted feel to the end result, and, for all that novelists aspire to naturalism, the reality they depict remains one largely devoid of the things that real people really do. Television watching is a case in point: the average Briton watches four hours of TV a day, yet I hardly ever read a novel in which any of the characters slumps in front of the television. Since its advent digital media has acquired an astonishing ubiquity: according to a recent survey, Britons now spend more time "viewing content" than we do sleeping. In attempting to accurately portray my characters' mental lives I've therefore drawn on the television, film and popular song of the period. Reading many serious novels, I get the impression that their characters only ever think about the finer things in life – grand emotions, weighty political and philosophic questions, spiritual doubts – whereas, if my own acquaintance (and my self-knowledge) is anything to go by, even the most high-minded among us spend significant portions of the day with our minds full only of this remotely generated content.

In my recent fiction I've tried to give form and substance to the hall of mirrors within which the modern psyche pirouettes and strikes attitudes; my characters watch films, remember their scenes and dialogue, and either consciously or unconsciously model their own behaviour on that of the actors whose performances they've witnessed. In a strange quirk of artistic depiction, this has already become a recherche exercise, for people no longer view movie stars in quite the same way. But in the same way that a period film made 50 years ago now seems dated in its conception of the past, so, I would argue, our realisation of our forebears is imperilled if we pay insufficient attention to the exact ephemera that preoccupied them – even when it no longer has any salience or relevance for us.

Slumbering fitfully as a result of the barbiturates he has stolen from the ship's doctor in order to avoid the horrors of alcohol withdrawal, my character Claude Evenrude is awakened to the hell of a successful torpedo attack on the USS Indianapolis by the Japanese submarine I-58. As he flounders across the burning deck, then slides down the scorching hull into the heaving, gelid waters, he sees monstrous apparitions launching themselves from the fantail: skin angels – men whose flesh has been flayed from them by fire and blast – and men who take wing only for a few seconds before they're swatted by the ship's slowly revolving propellers. The nightmarish vision recalls to Claude not the engravings of Gustave Doré, or verses from Dante's Inferno, but the slug-line with which a brand of insecticide is advertised on a popular radio show: "Quick, Henry! The flit!" Then, adrift in the water with the other survivors, Claude is visited not by biblical intimations of mortality and transcendence, but show tunes – specifically lines from the movie musical South Pacific. He may consider himself, as a Columbia University dropout, to be a cut above the prairie boys and hicks that – in his view – comprise the Indianapolis's crew, but as the sun beats down and the sharks rise up, he, like them is plagued by hallucinations of Ethel Merman, frolicking nude on a sable shore. As for those sharks, they attack the kid whose life jacket Claude has taken not in their own, all too embodied form, but as shadowy simulacra of the baddies in a popular contemporary serial, Captain Midnight.

I could go on: there are a plethora of film references, scenes and inter-leavings of the filmic and the purportedly real in Shark; the characters watch films, reenact films and quote their dialogue either consciously or unconsciously. In the 20th century, film provided us not only with a narrative form and a series of techniques that could be applied to the literary, but with a new method of shaping our sense of both individual and collective reality. And this is in keeping with the underlying themes of my trilogy; another way of looking at our at times wilful, but mostly unconscious substitution of the virtual for the real, is that it's a kind of disease. I had begun by thinking I would write Jaws without the shark; I ended up by writing Shark with quite a lot of Jaws.

• Shark by Will Self is published next month by Viking.