Friday, November 12, 2010

Tetris Helps Prevent Unpleasant Memories of Gory Film in Happy People

Most everything you've read about the Doctors Prescribing 'Tetris Therapy' study is wrong. That ridiculous headline, courtesy of "fair and balanced" Fox News, is the most egregious lie I could find [if you have other favorites, please leave links in the comments]. Press stories frequently distort research findings, but sometimes the authors themselves shoulder the most blame (Holmes et al., 2010). Misuse of the words "trauma" "flashback" "cognitive vaccine" and "PTSD" are at fault here.

The experiment in question is interesting as a memory study. It demonstrated that playing a visuospatial video game (Tetris) 30 min after a disturbing film can lessen intrusive visual memories, but playing a verbal trivia game (Pub Quiz) can have the opposite effect (Holmes et al., 2010). According to Baddeley (1992), this occurs because of two modality-specific working memory systems: the visuospatial sketchpad for visual working memory and the phonological loop for verbal working memory. Tetris interferes with the former, while Pub Quiz interferes with the latter.

Sixty participants (18–60 yrs old; mean age=27 yrs; 30 females) took part in Experiment 1. They were carefully screened for trauma history, mood, trait anxiety and depression. Potential subjects were excluded if they had ever been treated for mental illness of any kind. So this is a group of healthy controls -- not depressed, not anxious, minimal exposure to trauma, and no PTSD. They were a happy bunch, with mean scores on the Beck Depression Inventory (BDI) of 5.7-6.2.1

The participants were divided into three groups for the different treatment conditions, illustrated below.

Figure 1 (from Holmes et al., 2010). Experiment 1 study design overview.
Participants completed the trauma film paradigm, a well established experimental analog for PTSD. All participants viewed a traumatic film followed by a 30-min structured break. Participants were then allocated to one of three experimental conditions [Tetris vs. no-task control vs. Pub Quiz] which they completed for 10 min. Afterwards participants in the computer game conditions rated their enjoyment of the game. Flashbacks (involuntary memories) were monitored for 1 week using an intrusion diary. After 1 week, diary compliance was checked and a test of voluntary memory (recognition memory test) for the trauma film was administered.

What is the "trauma film paradigm"?
The 21-min film [previously used in 22] contained 15 clips of traumatic content including fatal road traffic accidents and graphic scenes of human surgery.
Following that link leads you to this description (and a series of other studies):
Participants were shown a 13 min film of real-life footage of the aftermath of road traffic accidents (compiled by Steil, 1996). This film has been used extensively in studies using the trauma film paradigm (e.g. Brewin and Saunders, 2001, Hagenaars et al., 2008, Halligan et al., 2002, Holmes et al., 2004, Holmes et al., 2006, Holmes and Steel, 2004 and Stuart et al., 2006). It consists of five separate scenes each introduced by a short commentary providing context for the scene.
To begin with, actual trauma isn't forewarned or contextualized in advance. It's surprising and shocking. Granted, ethical considerations require informing the participants at the time of recruitment, but this imposes even more limits as a model of real trauma.

Going back to the string of references, the first citation (Steil, 1996) indicates the author studied "Posttraumatic intrusions after road traffic accidents" (not merely watching a road traffic accident film). Nonetheless, let's quickly review some of the other papers, with an eye on the terminology used by the respective authors. Brewin and Saunders (2001) looked at "intrusive memories for a stressful film". Hagenaars et al. (2008) reported on "the development of intrusions after an aversive film". In 2004, Holmes et al. studied "intrusive memory development". Notice that "traumatic" and "flashbacks" aren't yet part of the lexicon. As time went on, Holmes et al., 2006 called it a "traumatic film" but hadn't yet transformed "intrusive memories" into "flashbacks". The language used to describe the experimental phenomena shapes the reader's willingness to view the film paradigm as a proxy for real trauma.

What is a true flashback? Here's the relevant section of the DSM-IV Criteria for Posttraumatic Stress Disorder, which describes a flashback episode as a complex, multi-sensory experience and not just a visual memory:
(3) acting or feeling as if the traumatic event were recurring (includes a sense of reliving the experience, illusions, hallucinations, and dissociative flashback episodes, including those that occur upon awakening or when intoxicated).
Another element of these experimental designs can include ratings of how upset the participants were while viewing the gory film (Holmes et al., 2004):
Participants rated their distress associated with viewing the film after it had ended. They also rated their level of depression, anger, happiness, and anxiety both pre- and postfilm. Eleven-point scales were used, with anchors of 0 (not at all) and 10 (extremely).
In that study, ratings were 5.1 for a "no task" condition that did not involve a secondary task while watching the video. So these participants were not especially distressed. Furthermore, this unvalidated self-rating scale has no clinical relevance to PTSD. Eleven-point scales were also used to rate [non-clinical] levels of depression, anger, happiness, and anxiety both pre- and postfilm.

Finally, to illustrate that the "trauma film paradigm" bears no relation to the lasting effects of real trauma that can cause PTSD is this ethical clarification (Holmes et al., 2004):
With respect to the ethical issues of showing a film with traumatic content, we note that previous studies using the same trauma film (Brewin & Saunders, 2001; Murray, 1997), as well as those using other trauma films (e.g., Davies & Clark, 1998), found that no participants reported ongoing distress subsequent to the end of the experiment. Further, although transiently distressing, the film content is similar to that witnessed by television viewers watching programs such as news coverage of road traffic accidents, or programs about the police or ambulance service work.
I'm not dismissing the possibility that therapies based on these experimental parameters may eventually have clinical usefulness. What I'm suggesting is that the authors show more restaint in their use of terminology (e.g., immediately calling their experimental task a "cognitive vaccine"), and in their extrapolation of experimental findings in healthy subjects to effective treatments for those suffering from PTSD.

Thanks to Sandra of Channel N for helpful discussions.


1 Scoring for the BDI-II is: 0–13: minimal depression; 14–19: mild depression; 20–28: moderate depression; and 29–63: severe depression.


Baddeley A. (1992). Working memory. Science 255:556-9.

Holmes EA, Brewin CR, Hennessy RG. (2004). Trauma films, information processing, and intrusive memory development. J Exp Psychol Gen. 133:3-22.

Holmes, E., James, E., Kilford, E., & Deeprose, C. (2010). Key Steps in Developing a Cognitive Vaccine against Traumatic Flashbacks: Visuospatial Tetris versus Verbal Pub Quiz. PLoS ONE, 5 (11) DOI: 10.1371/journal.pone.0013706

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At November 14, 2010 12:21 PM, Anonymous Brittany Mcintyre said...

Thanks for clarifying & elaborating on the methods used & results of this study. I came across so many news sources today that definitely skewed the results of the study-like the Fox News story you mentioned. Your explanation of the study makes a lot more sense and presents an idea that I can actually buy in to.

I wanted to share a video I thought you might like, I hope you’ll consider embedding or linking to the video in your post:
The video combines clips & quotes from a few different news sources that commented on the study results. gathers information from various news outlets, and puts it together to provide multiple views of news stories. analyzes the information, with the goal of providing a diverse perspective of the story to those that might normally receive their news from a single source.

If you have any questions or concerns, feel free to email me.

Brittany McIntyre

At November 15, 2010 4:51 AM, Blogger Neuroskeptic said...

Studying trauma is obviously something which is ethically difficult. My understanding is that the films used by Holmes et al are pretty nasty, and (unlike a horror movie) are based on real events, which makes them a lot more striking. most people will experience some degree of "intrusive memories" in the sense of remembering them in the following days "out of the blue", but yes, it's a long way from that to real PTSD flashbacks.

Still, you can't blame the authors really. It's a lot easier to get funding for a memory study that's relevant to PTSD, than just a pure memory study... "let he who has never exaggerated the clinical relevance of his work, cast the first stone"

At November 16, 2010 9:11 AM, Anonymous Pierce R. Butler said...

... actual trauma isn't forewarned or contextualized in advance.


"Get some sleep, men: we're going on foot patrol in Sadr City at 0400 hours."

"You bitch, when I get you home I'm going to ..."


At November 18, 2010 2:46 AM, Anonymous Anonymous said...

Thanks for that post!

At least now I know that tetris might help if I have watched a film from which I wish to "unsee" some scenes. Gonna give it a try next time.

At November 19, 2010 5:18 AM, Blogger Neuroskeptic said...

Pierce R Butler: But you never know in advance what horrible thing will happen. e.g. if you're going on patrol in Sadr city you don't know if you're going to see nothing at all, see your buddy get shot, or get blown up yourself.

Also, it might be that "forewarned" traumas are less likely to cause PTSD than out of the blue ones. I don't know. that would be an interesting study actually.

At November 19, 2010 11:08 PM, Blogger The Neurocritic said...

Neuroskeptic - Thanks for such a reasonable reply to Pierce R. Butler.

As for overselling the clinical relevance, I found it interesting to trace the authors' own depiction of their work.

At January 30, 2013 9:19 PM, Anonymous Anonymous said...

This study seems to imply that training in Tetris 3D leads to bigger changes (although I cannot access the full article)

At January 30, 2013 9:52 PM, Blogger The Neurocritic said...

Thanks for the link, looks interesting!


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