In a famous passage in Theatetus, Plato compares human memory to a wax tablet:

Whenever we wish to remember anything we see or hear or think of in our own minds, we hold this wax under the perceptions and thoughts and imprint them upon it, just as we make impressions from seal rings; and whatever is imprinted we remember and know as long as its image lasts, but whatever is rubbed out or cannot be imprinted we forget and do not know.

The appeal of Plato’s metaphor is that it fits our intuitions about memory. Like the ancient philosopher, we’re convinced that our recollections are literal copies of experience, snapshots of sensation written into our wiring. And while our metaphors of memory now reflect modern technology – the brain is often compared to a vast computer hard drive – we still focus on comparisons that imply accurate recall. Once a memory is formed, it’s supposed to stay the same, an immutable file locked away inside the head.

But this model is false. In recent years, neuroscientists have increasingly settled on a model of memory that represents a dramatic break from the old Platonic metaphors. It turns out that our memories are not fixed like an impression in a wax tablet or a code made of zeroes and ones. Instead, the act of remembering changes the memory itself, a process known as memory reconsolidation. This means that every memory is less like a movie, a collection of unchanging scenes, and more like a theatrical play, subtly different each time it’s performed.

On the one hand, the constant reconsolidation of memory is unsettling. It means that our version of history is fickle and untrustworthy; we are all unreliable narrators. And yet, the plasticity of memory also offers a form of hope, since it means that even the worst memories can be remade. This was Freud’s grand ambition. He insisted that the impossibility of repression was the “corner-stone on which the whole structure of psychoanalysis rests.” Because people could not choose what to forget, they had to find ways to live with what they remembered, which is what the talking cure was all about.

If only Freud knew about video games. That, at least, is the message of a new paper in Psychological Science from a team of researchers at Cambridge, Oxford and the Karolinska Institute. (The first author is Ella James; the corresponding author is Emily Holmes.) While previous research has used beta-blockers to weaken traumatic memories during the reconsolidation process – subjects are given calming drugs and then asked to remember their traumas – these scientists wanted to explore interventions that didn’t involve pharmaceuticals. Their logic was straightforward. Since the brain has strict computational limits, and memories become malleable when they’re recalled, distracting people during the recall process should leave them with fewer cognitive resources to form a solid memory trace of the bad stuff. “Intrusive memories of trauma consist of mental images such as visual scenes from the event, for example, the sight of a red car moments before a crash,” write the scientists. “Therefore, a visuospatial task performed when memory is labile (during consolidation or reconsolidation) should interfere with visual memory storage (as well as restorage) and reduce subsequent intrusions.” In short, we’ll be so distracted that we’ll forget the pain.

The scientists began by inducing some experimental trauma. In the first experiment, the “trauma” consisted of a 12 minute film containing 11 different scenes involving “actual or threatened death, as well as serious injury.” There was a young girl hit by a car, and a man drowning in the sea and a teenager, staring at his phone, who gets struck by a van while crossing the street. The subjects were shown these tragic clips in a dark room and asked to imagine themselves “as a bystander at the scene.”

The following day, the subjects returned to the lab and were randomly assigned to two groups. Those in the first group were shown still pictures drawn from the video, all of which were designed to make them remember the traumatic video. There was a photo of the young girl just before she was hit and a snapshot of the man in the ocean, moments before he slipped below the surface. Then, after a brief “music filler task” – a break designed to let the chemistry of reconsolidation unfold – the subjects were told to play Tetris on a computer. Twelve minutes later, they were sent home with a diary and asked to record any “intrusive memories” of the traumatic film over the following week.

Subjects in the control group underwent a simpler procedure. After returning to the lab, they were given the music filler task and told to sit quietly in a room, where they were allowed to “think about anything.” They were then sent home with the same diary and the same instructions.

As you can see in the charts below, that twelve minute session of Tetris significantly reduced the number of times people remembered those awful scenes, both during the week and on their final return to the lab:

A second experiment repeated this basic paradigm, except with the addition of two additional control groups. The first new group played Tetris but was not given the reactivation task first, which meant their memories never became malleable. The second new control group was given the reactivation task but without the Tetris cure. The results were again compelling:

It’s important to note that the benefits of the Tetris treatment only existed when the distraction was combined with a carefully timed recall sequence. It’s not enough to play a video game after a trauma, or to reflect on the trauma in a calming space. Rather, the digital diversion is only therapeutic within a short temporal window, soon after we’ve been reminded of what we’re trying to forget. "Our findings suggest that, although people may wish to forget traumatic memories, they may benefit from bringing them back to mind, at least under certain conditions - those which render them less intrusive," said Ella James, in an interview with Psychological Science.

The virtue of this treatment, of course, is that it doesn’t involve any mood-altering drugs, most of which come with drawbacks and side-effects. (MDMA might be useful for PTSD, but it can also be a dangerous compound.) The crucial question is whether these results will hold up among people exposed to real traumas, and not just a cinematic compilation of death and injury. If they do, then Tetris just might become an extremely useful psychiatric tool.

Last point: Given the power of Tetris to interfere with the reconsolidation process, I couldn’t help but wonder about how video games might be altering our memory of more ordinary events. What happens to those recollections we think about shortly before disappearing into a marathon session of Call of Duty or Grand Theft Auto V? Are they diminished, too? It’s a dystopia ripped from the pages of Infinite Jest: an entertainment so consuming that it induces a form of amnesia. The past is still there. We just forget to remember it.

James, Ella L., et al. "Computer game play reduces intrusive memories of experimental trauma via reconsolidation-update mechanisms." Psychological Science (2015)