How horror films manipulate our senses: 'I swore I’d never allow myself to be drawn back into the cinema'

My first trip to the cinema was nearly my last. On Christmas Eve 1996, a friend’s dad took a group of us – aged variously between four and six – to the ABC Cinema in Streatham for an afternoon showing of Matilda. An avid Roald Dahl fan, I was excited to see one of my storybook heroes transported to this giant screen, the scale of which I could barely comprehend. And everything started out just fine: the magic of the book was just as real with a budget of $36m behind it, and Embeth Davidtz made a perfectly acceptable Miss Honey. But then, somewhere around the halfway point, something happened that shook the five-year-old me to his tiny core.

Matilda and Miss Honey, seeking the return of a stolen painting, had broken into the home of Agatha Trunchbull, Matilda’s impossibly wicked headmistress, played in the film by Pam Ferris from The Darling Buds of May (the irony of her casting was lost on me at the time). As they explored the house, The Trunchbull suddenly returned, sending the pair scrabbling for an exit. Matilda ducked down a darkened staircase into the cellar and The Trunchbull barrelled down after her, screaming as she went. Paint cans toppled from their shelves, the soundtrack rose to a fever pitch and I sunk, terrified, into my seat.

In that moment, I swore I’d never allow myself to be drawn back into the cinema. It was a promise to which I briefly held true, abstaining from moviegoing for more than a year until my all-consuming love of Nickelodeon duo Kenan & Kel tempted me into a Sunday afternoon matinee of Good Burger. The ABC Streatham has since been converted into luxury flats. But the memory of that Christmas trip still looms large over my relationship with cinema, even now as I pursue a career in the industry my pre-teen self was so keen to write off.

My new film Fear Itself, available now on the BBC iPlayer, is an attempt to make sense of those moments when the connection between a film and its audience feels palpably, viscerally real. Constructed entirely from existing horror films, it’s a journey through fear and cinema that – with any luck – not only scrutinises that sensation, but attempts to conjure it. I think some part of me even hopes there’s a five-year-old watching it somewhere and having a similarly formative fright as a result.

It seems strange that Pam Ferris is now filed in my subconscious alongside real-world instances of isolation, threat or menace from my past which – free from the mitigating security of the cinema environment – should surely hold greater sway over my psyche. But then that’s precisely why fear is such a powerful cinematic tool: in the moment it occurs, there’s nothing rational about it. Your conscious mind may recognise the relative safety of your situation, but your nervous system doesn’t care. Goose pimples still ripple across the surface of your skin, long before your brain can relay the news that Paranormal Activity 3 – for all its lo-fi ingenuity – can’t actually do you any bodily harm.

Perhaps that’s why even the most cerebral horror movies are so preoccupied with sensory matters. A meditative arthouse thriller like Under the Skin may appear, on the surface, to have little in common with your average multiplex slasher outing, but it’s no coincidence that when Scarlet Johansson’s murderous humanoid alien prowls the streets of Glasgow in search of prey, she does so under the menacing cover of night. In low light, the limitations of our senses render the world a more uncertain place, filled with half-seen figures and eerie, inexact spaces. The colour-sensitive cones in our eyes lose ground to the light-sensitive rods, which are concentrated around the edges of the retina. The result is a monochrome vision of the world, where even the slightest movement in the corner of your eye is amplified tenfold. For millennia, this sensation has inspired folk tales of colourless apparitions, lingering in the shadows. Today, it inspires horror movies.

An awareness of human biology can be detected at every level of horror filmmaking, from sound editing to set design. The colour red has a uniquely potent effect on the human mind, conjuring up a feeling of fear and intimidation even when divorced from any real threat. Is it any wonder then that horror cinema’s default colour palette is soaked in vermilion tones, from the blood-red coat worn by the mysterious figure that stalks Donald Sutherland across the Venice canals in Don’t Look Now to the magenta-hued hallucinations that plague the haunted protagonist of Marnie, and even the scarlet pullover favoured by Freddy Krueger?

Our sensitivity to sound is even more vulnerable to manipulation. We unthinkingly accept the reality of a film’s soundscape, never stopping to consider the thousands of infinitesimally small noises from which it’s built. As a result, even the slightest sonic provocations can catch us entirely off guard. A 2010 University of California study found that non-linear sounds – those that go beyond the limits of an instrument’s normal musical range, like the squeal of a horn blown too hard – appear frequently in horror movie soundtracks, perhaps most famously in the screechy, violin-soaked shower scene from Psycho. Their similarity to the noises produced by animals under duress, the study concluded, triggered a powerful instinctive fear response in us.

French director Gaspar Noé confessed in a 2003 interview that he and composer Thomas Bangalter inserted infrasound – a layer of sub-bass noise below the range of the human ear – into his film Irreversible in order to inspire a feeling of dread in the audience before a particularly gruesome scene. Such sounds could theoretically cause an entire auditorium to tremble, or strike the resonant frequency of a viewer’s chest wall, while giving the illusion of complete silence. “You can’t hear it,” Noé observed, “but it makes you shake.” You’d be forgiven for assuming such a power is beyond the scope of cinema, and instead mistaking the sensation for some kind of sixth sense.

During the sound mix of Fear Itself, there were moments when I found myself disagreeing with other members of the crew over elements of the soundtrack, especially when they approached the limits of human hearing, as a high-pitched ringing does, or a low, droning hum. Not because of artistic differences, but because our ears perceived the sounds flowing from the speakers in minutely different ways.

To me, that’s what makes horror’s manipulation of our senses most fascinating: it reminds you that cinema, and the hyper-sensory world of horror cinema in particular, is an entirely subjective experience, defined by the neurological tunings of each individual viewer.

Ultimately, our relationship with horror is a symbiotic one: the scares brought to life on the screen are made possible by our ability to receive them, just as 3D filmmaking relies on the ability of the human mind to take two images and construct a three-dimensional reality from them – and stereo sound makes sense only in a world where I have an ear on either side of my head.

As the horror genre settles into its second century, self-appointed moral guardians continue to insist that scary movies have the power to deprave and corrupt the individuals who watch them, but I suspect they’re less adept at implanting horrors within our minds than at drawing out those already lying dormant within. Which might explain why, two decades on, I still can’t bring myself to revisit Matilda: because I may be 3ft taller than I was that Christmas, but whatever instincts within me were rattled by the sights and sounds of Pam Ferris crashing down those cellar steps are still there, waiting to be triggered again.

Fear Itself is available on BBC iPlayer now