Can Tetris cut unwanted trauma memories but keep normal recall?
Playing Tetris after a reminder of a distressing film reduced how often scenes from it popped into mind unbidden, while people's deliberate memory for the film stayed just as good.
Source
Intrusive memories and voluntary memory of a trauma film: Differential effects of a cognitive interference task after encoding
Study at a glance
- Design
- Human experiment — Three between-group experiments: healthy adults watched a 12-minute trauma film, then 30 minutes later saw film reminder stills followed by 10 minutes of Tetris or sitting quietly (plus a Tetris-only group in Experiment 3).
- N
- N=139 · 46 in Experiment 1 (23 per group), 36 in Experiment 2 (18 per group), 57 in Experiment 3 (19 per group across three groups); n is the sum across the three experiments.
- Population
- Healthy adult volunteers from the MRC Cognition and Brain Sciences Unit panel in Cambridge, UK, with no reported history of mental, neurological or psychiatric illness.
- Outcome
- Number of intrusive memories of the film (1-week diary and lab vigilance-intrusion task) versus voluntary memory (free recall, recognition), perceptual priming and attentional bias to film stills.
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What they did
Across three experiments, adults watched a 12-minute film of real injuries and deaths, waited 30 minutes, then saw a still from each scene and either played Tetris for 10 minutes or sat quietly. Memory was then tested with measures chosen to rule out boring explanations for why only intrusions change: free recall and recognition (voluntary memory), a perceptual priming task, a dot-probe test of attention to film cues, and intrusions counted either in a week-long diary or during a boring digit-watching task in the lab. Experiment 3 added concurrent verbal or visuospatial working-memory load while intrusions were counted, and a group that played Tetris without the reminder.
What they found
The reminder-plus-Tetris group consistently had fewer intrusions, with large effects (for example d = 1.23 for the Experiment 2 diary and d = 1.20 for lab intrusions in Experiment 3), and the reduction showed up within minutes in the lab as well as a week later. There was no group difference in recognition, free recall, perceptual priming or attentional bias toward film stills, and statistical interactions confirmed the effect was specific to intrusions. Concurrent working-memory load reduced intrusions for everyone but did not change the size of the Tetris effect, and Tetris without the reminder cue did not reduce intrusions.
The limits
What it doesn't show
Participants were healthy volunteers watching a film, not people who had lived through a real trauma, so the size of the effect in clinical settings is not established here. All memory tasks were given in a fixed order and the study was powered for the intrusion effect, so small effects on other measures could have been missed (though they trended the opposite way). The authors can only rule out the three retrieval factors they tested; another unmeasured difference between intrusion and voluntary-memory tasks could still explain the dissociation, and intrusions rely on self-report.
Key terms
- Intrusive memory
- A sensory memory of an event, often an image, that pops into mind involuntarily; the hallmark symptom of PTSD.
- Trauma film paradigm
- A lab analogue of trauma in which healthy people watch distressing footage so that later intrusions can be studied ethically.
- Single-trace theory
- The view that intrusive and voluntary memories come from the same stored memory and differ only in how they are retrieved.
- Separate-trace theory
- The view, e.g. dual representation theory, that intrusions draw on a memory representation distinct from the one used for deliberate recall.
- Cue overlap
- How closely the cues present at retrieval match what was present at encoding; higher overlap makes retrieval easier.
- Perceptual priming
- Faster or easier processing of something previously seen, even without deliberately remembering it.
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Quiz yourself
Which outcome did reminder-plus-Tetris reliably reduce across the experiments?
Common questions
Why does it matter that voluntary memory was unaffected?
A useful trauma intervention should stop unwanted flashbacks without erasing the person's ability to deliberately remember and report what happened, for example to police or a therapist.
Was it just playing any game that helped?
No. In Experiment 3, people who played Tetris without first seeing reminder stills had about as many intrusions as those who only saw reminders, so the reminder plus the game together seemed necessary.
Does this prove intrusions come from a separate memory system?
Not conclusively. It rules out three obvious retrieval-based explanations, which makes separate-trace accounts more plausible, but other untested differences between tasks remain possible.
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