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Memory · Reconsolidation

Intrusive memories can be reduced after they have already consolidated

Evidence: StrengtheningThis development added evidence in the direction the field already leaned. What the labels mean

Study published Jul 1, 2015. PaperFren added this explanation Sep 12, 2026.

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Short answer

After a consolidated analogue trauma memory was reactivated, Tetris reduced later intrusions; neither reminder nor game play worked alone, and recognition of the film was unchanged.

What happened

James, Holmes and colleagues showed 52 then 72 adults a trauma film and waited 24 hours so the memory could consolidate. Only the group that saw reminder stills, waited 10 minutes, then played Tetris for 12 minutes had fewer intrusive images over the following week (Experiment 1 d = 1.14 vs no-task control). Experiment 2 found the same pattern against Tetris-only (d = 0.84) and reactivation-only (d = 1.11) groups. Recognition memory for the film stayed intact.

Why it matters

This is not a claim that Tetris treats PTSD. It is evidence that involuntary visual intrusions — not the factual record of an event — can be altered in a reconsolidation window, and that both reactivation and a competing visuospatial task appear necessary.

Evidence

Study type
Laboratory experiments with a trauma-film analogue (two between-groups experiments)
Sample
Experiment 1 n = 52; Experiment 2 n = 72 (18 per group)
Journal
Psychological Science · peer reviewed
Replication
Not assessed in this corpus beyond the paper's own Experiment 2 replication of Experiment 1
Limitations
Analogue trauma film, not clinical PTSD; only Tetris was tested; modality specificity remains open; recognition was spared so the memory was not erased.

What this connects to

Sources

The 2 studies this explanation is built from, by the role each plays. Every source links to PaperFren’s explanation of it and to the original paper.

Primary study

  • Can playing Tetris reduce intrusive memories of trauma?

    James EL, Bonsall MB, Hoppitt L, et al. · 2015 · Psychological science · 190 citations

    Playing a visuospatial computer game like Tetris after reactivating a consolidated emotional memory significantly reduces the frequency of subsequent involuntary intrusions.

    What it does not show

    First, this study relied on an analogue trauma model using a distressing video, which does not fully replicate the clinical complexity, severity, or real-world environment of experiencing an actual life-threatening traumatic event. Second, the study did not compare Tetris with other types of games, leaving it unclear if the effect is specific to visuospatial tasks or if any highly engaging cognitive task (like a verbal game) would produce similar results. Finally, because recognition memory for the film remained fully intact, the intervention did not erase the memory itself, meaning the cognitive mechanism only prevents the memory from involuntarily intruding.

    PaperFren explanationOriginal paper (DOI)cc by

Supporting evidence

  • Does smiling unconsciously make negative memories feel less sad?

    Arminjon M, Preissmann D, Chmetz F, et al. · 2015 · Frontiers in psychology · 13 citations

    Forcing an unconscious smile while remembering a sad story reduces how negative that memory feels later without hurting factual recall of the event.

    What it does not show

    The study does not show if the shift in emotional tone is permanent, as the final memory test occurred only a 2-min delay after the facial manipulation. It cannot rule out whether a full 24-h delay is required to permanently lock in this new emotional evaluation. Additionally, the sample was limited to healthy young university students, meaning the results might not automatically apply to clinical populations suffering from severe trauma or post-traumatic stress disorder.

    PaperFren explanationOriginal paper (DOI)cc by

Before

Most cognitive-task work on trauma-film intrusions targeted the hours after encoding, when memories are still consolidating. Clinical translation needs a way to touch memories that have already stabilized.

Now

This pair of experiments shows a reconsolidation-consistent pattern: reactivation plus a visuospatial task reduced subsequent intrusions of an already-consolidated analogue memory. The authors are explicit that a trauma film is not a life-threatening event and that other games were not tested.