Could the technology in Eternal Sunshine soon become reality?

Valentine’s Day, 2004. Joel (Jim Carrey) is about to board a train to work. Then, out of nowhere, he darts through the sea of commuters, bolting onto the platform opposite, and forces himself through the closing doors of a train bound for Montauk. He sits in a carriage which is empty, save for a blue-haired woman in a bright orange hoodie who later introduces herself as Clementine (Kate Winslet). “No jokes about my name,” she quips. He’s perplexed. “I don’t know any jokes about your name.” She sings ‘Clementine’, a folk tune used in the cartoon show Huckleberry Hound, but Joel says he’s never heard of it. “What are you, nuts?” says Clem.

Soon enough, we learn that this isn’t the first time Clementine and Joel have met – and that Joel has actually watched Huckleberry Hound. But when we first see the pair in the opening scenes of Michel Gondry’s 2004 film Eternal Sunshine of the Spotless Mind, both have recently had their memories of each other wiped by Lacuna, Inc., a fictional firm where people can have painful memories deleted from their brains forever.

The film, which was released exactly 20 years ago this week, follows Joel, a painfully milquetoast man, as he decides to wipe his free-spirited ex-girlfriend Clem from his memory after finding out that she has erased him from hers. The majority of the film takes place inside Joel’s brain while he is sedated during the erasing procedure: as he relives happier times with Clem, he comes to regret his decision and attempts to thwart the erasers’ efforts by clinging onto his memories of the relationship.

The film has since become a cult classic. It continues to strike a chord with anyone who has found themselves in the painful, piercing throes of heartbreak and fruitlessly wished that the whole relationship had never happened at all. Eternal Sunshine’s enduring appeal lies in the fact that it grapples with the questions we always ask ourselves in the aftermath of a break-up: what if I could erase the pain? Were the good times even worth this much suffering? Would it have been better if none of this ever happened?

Eternal Sunshine’s depiction of heartbreak is so resonant it transcends time, but a lot has changed in the two decades since its release. In the film there are no smartphones, no social media platforms, and there’s barely any internet. After their (second) first date, Clem writes her number on Joel’s arm using a Sharpie, and when he gets home he has to contort his body to read it as he punches the digits into a chunky landline phone. Against this backdrop, the idea of memory-altering technology seems genuinely futuristic.

Today, we’re still a long way from a world where a company like Lacuna exists. There’s little chance that in near future you’ll be able to walk into a clinic, sign some forms, and allow a crack team of neuroscientists to scrub every memory of your softboi ex from your brain (unfortunately). But we’re certainly closer to being able to use science to alter your memories than we were 20 years ago.

Just three years after the release of Eternal Sunshine, researchers found that injecting an ‘amnesia drug’ could take the emotional sting out of unpleasant memories. Then in 2009, a team at the University of Toronto succeeded in essentially selectively erasing memories in mice by injecting a toxin into the amygdala, the part of the brain which processes emotions. Since then, a number of different methods for manipulating memories have been studied by psychologists and neuroscientists across the world, such as inhaling xenon gas, taking propranolol, using lights, and playing sounds to people while they sleep.

Dr Sheena Josselyn co-led the research team which succeeded in erasing the memories of mice and has spent decades researching the way memories work. Does she think the technology used in Eternal Sunshine could one day be commonplace? “This is a tricky question,” she says. “We now have the technology to do this in mice. But it is very invasive. Can we ever do this in people? And would we want to?” She explains that memory-erasing technology could be useful for people with memories that interfere with their day-to-day lives, such as people with PTSD. “Right now, it is not possible to do this in humans,” she says. “But the proof of concept is there from the work from many labs across the world using rodents [...] With the aid of many hard-working scientists across the world, science fiction is becoming science fact.”

Dr Aidan Horner has also extensively researched the science behind our memories, and was the senior author of the study into how playing ‘sound cues’ during sleep could help people forget painful experiences. He agrees with Dr Josselyn that memory-weakening technology could be helpful for people with conditions such as PTSD. “Some individuals struggle to cope with specific traumatic memories and these memories often come to mind uninvited. It is possible that by weakening them we could reduce these memory intrusions or reduce the emotional strength of the memory,” he says.

It’s encouraging to think that memory-altering technology could one day be used to help people overcome genuinely traumatic experiences – but is it possible that, in the future, anyone with the means to pay for it could be able to edit their memories as they please? Dr Horner hopes not. “Allowing individuals in a non-clinical setting to decide to ‘erase’ specific memories – if that was ever possible – simply because they caused some degree of emotional discomfort would seem less desirable,” he says. Dr Josselyn agrees. “It is not a great idea to do ‘cosmetic memory surgery’ and try and erase slightly embarrassing memories,” she says. “For instance, it is the memory of how embarrassed I was the last time I tried karaoke that keeps me from doing it again! So even aversive memories are important. Some believe we are the sum total of our memories and that messing with memories changes who we are.”

Isn’t this the film’s message, too? After Clem and Joel reunite and learn what has happened to them both, Joel runs after a distraught Clem and suggests that they give their relationship another go. “I can’t see anything that I don’t like about you,” he says. “But you will,” Clem hits back. “You’ll think of things, and I’ll get bored with you and feel trapped because that’s what happens with me.” We know she’s right, having watched their previous relationship disintegrate for these exact reasons. The film then ends with a looped clip of Clem and Joel running down the beach in Montauk, which some viewers have interpreted as a hint that without being able to learn from their past mistakes, Clem and Joel are doomed to break up again, and again, and again. It’s a reading of the film which tracks with screenwriter Charlie Kaufman’s original, darker script, which ends with an elderly Clem erasing Joel from her memory for the 15th time.

Ultimately, Eternal Sunshine reminds us that we need our bad memories to learn from our mistakes and appreciate the good times – and thankfully, scientists researching memory manipulation are well aware of this. “We are a long way from potential implementation, but that shouldn’t stop us from thinking about these issues,” Dr Horner says. “As techniques in this area develop, scientists will need to work closely with experts in mental health, ethics, and policy to ensure we get this right.”