Oli Scarff/Getty Images

In a follow-up study to their original 2009 research, Oxford University scientists found that playing Tetris after a traumatic event may help prevent flashbacks, the intrusive and unwanted memories of trauma that are the hallmark of posttraumatic stress disorder. They also found that this protective effect may be unique to Tetris; when another computer game was tested, it made people’s flashbacks worse.

In the first of two experiments, researchers had 60 adults (aged 18 to 60) with no history of mental health problems watch a 21-minute film containing traumatic content, like fatal traffic accidents and bloody scenes of human surgery. Such unsettling images — here, a stand-in for real trauma — can be haunting enough to produce mild flashbacks after viewing. Thirty minutes after the film, participants were randomly assigned to three 10-minute tasks: playing Tetris, playing another computer game called Pub Quiz, or just sitting quietly. (More on Time.com: How We Can Prevent Some Cases of PTSD)

During the 10-minute intervention, the researchers found that people in the Tetris group reported fewer flashbacks of images from the film than people in the Pub Quiz and do-nothing groups (there was no difference between the latter two).

Over the following week, the volunteers were also asked to keep a flashback diary, recording when and what memories from the film intruded their thoughts. As the researchers expected, people who played Tetris were significantly less likely to flash back to the movie than people in the no-task group. But more interesting: the volunteers who played Pub Quiz had significantly more flashbacks than either those who did nothing or played Tetris.

The authors theorize that engaging in a visual task like Tetris can be protective after a traumatic event because it interferes with the brain’s ability to lay down visual memories — the same harrowing images that could later return as flashbacks. A game like Pub Quiz, on the other hand — which involves answering general knowledge questions like “How many sides has a rhombus?” — is primarily verbal and conceptual, rather than visual. So Pub Quiz not only fails to prevent the brain from coding visual memories, it also competes with the brain’s verbal efforts to make sense of the trauma and deal with it. That explains why the Pub Quiz group fared even worse than the control group that sat quietly. (More on Time.com: Study: Why Child Abuse Investigations Don’t Help Kids)

The study’s second experiment was essentially the same as the first, except researchers extended the time between the movie and the computer-game task to four hours. Again, Tetris appeared to shield participants from flashbacks during the following week, even though they played the game hours instead of minutes after the traumatic event. “We account for this based on current models of memory consolidation indicating that certain types of memory may be malleable for up to 6 hours,” the authors note.

The researchers suggest that if further research bears out their findings, Tetris, or a visual-spatial task like it, could be developed as a kind of “cognitive vaccine” against flashbacks. It could be used as an alternative to other early interventions such as drug treatment and counseling, neither of which has shown much benefit.

The only question is, what’s the treatment for Tetris flashbacks?

More on Time.com:

Dude Where’s My Trauma? Marijuana Could Treat PTSD

5 Ways to Beat the Winter Doldrums

Babies Versus Bullies: Why Little Ones Can Help