Try to spot the flaw in this study. A scientist recruits a group of subjects to test the effectiveness of a new drug that purportedly improves attention. After giving subjects a pre-test to measure their attention, the experimenter tells the subjects all about the exciting new pill, and after they take the pill, the experimenter re-tests their attention. The subjects show significantly better performance the second time they’re tested.
This study would never pass muster in the peer review process—the flaws are too glaring. First, the subjects are not blind to the hypothesis—the experimenter told them about the exiting new drug—so they could be motivated to try harder the second time they take the test. The experimenter isn’t blind to the hypothesis either, so they might influence subject performance as well. There’s also no placebo control condition to account for the typical improvement people make when performing a task for the second time. In fact, this study lacks all of the gold-standard controls needed in a clinical intervention.
A couple years ago, +Walter Boot, Daniel Blakely and I wrote a paper in Frontiers in Psychology that describes serious flaws in many of the studies underlying the popular notion that playing action video games enhances cognitive abilities. The flaws are sometimes more subtle, but they’re remarkably common: None of the existing studies include all the gold-standard controls necessary to draw a firm conclusion about the benefits of gaming on cognition. When coupled with publication biases that exclude failures to replicate from the published literature, these flaws raise doubts about whether the cumulative evidence supports any claim of a benefit.
The evidence in favor of a benefit from video games on cognition takes two forms: (a) expert/novice differences and (b) training studies.
The majority of studies compare the performance of experienced gamers to non-gamers, and many (although not all) show that gamers outperform non-gamers on measures of attention, processing speed, etc (e.g., Bailystock, 2006; Chisholm et al., 2010, Clark, Fleck, & Mitroff, 2011; Colzato et al., 2010; Donohue, Woldorff, & Mitroff, 2010; Karle, Watter, & Shedden, 2009; West et al., 2008). Such expert/novice comparisons are useful and informative, but they do not permit any causal claim about the effects of video games on cognition. In essence, they are correlational studies rather than causal ones. Perhaps the experienced gamers took up gaming because they were better at those basic cognitive tasks. That is, gamers might just be better at those cognitive tasks in general, and their superior cognitive skills are what made them successful gamers. Or, some third factor such as intelligence or reaction times might contribute to interest in gaming and performance on the cognitive tasks.
Fortunately, only a few researchers make the mistake of drawing causal conclusions from a comparison of experts and novices. Yet, almost all mistakenly infer the existence of an underlying cognitive difference from a performance difference without controlling for other factors that could lead to performance differences. Experts in these studies are recruited because they are gamers. Many are familiar with claims that gamers outperform non-gamers on cognition and perception tasks. They are akin to a drug treatment group that has been told how wonderful the drug is. In other words, they are not blind to their condition, and they likely will be motivated to perform well. The only way around this motivation effect is to recruit subjects with no mention of gaming and only ask them about their gaming experience after they have completed the primary cognitive tasks, but only a handful of studies have done that. And, even with blind recruiting, gamers might still be more motivated to perform well because they are asked to perform a game-like task on a computer. In other words, any expert-novice performance differences might reflect different motivation and not different cognitive abilities.
Even if we accept the claim that gamers have superior cognitive abilities, such differences do not show that games affects cognition. Only by measuring cognitive improvements before and after game training might a causal conclusion be justified (e.g., Green & Bavelier, 2003; 2006a; 2006b, 2007). Such training studies are expensive and time-consuming to conduct, and only a handful of labs have even attempted them. And, at least one large-scale training study has failed to replicate a benefit from action game training (Boot et al., 2008). Yet, these studies are the sole basis for claims that games benefit cognition. In our Frontiers paper, we discuss a number of problems with the published training studie. Taken together, they raise doubts about the validity of claims that games improve cognition:
- The studies are not double-blind. The experimenters know the hypotheses and could subtly influence the experiment outcome.
- The subjects are not blind to their condition. A truly blind design is impossible because subjects know which game they are playing. And, if they see a connection between their game and the cognitive tasks, then such expectations could lead to improvements via motivation (a placebo effect). Unless a study controls for differential expectations between the experimental condition and the control condition, then it does not have adequate control for a placebo effect explanation for any differences. To date, no study has controlled for differential expectations.
- Almost all of the published training studies showing a benefit of video game training relative to a control group show no test-retest effect in the control group. That's bizarre. The control group should show improvement from the pre-test to the post-test—people should get better with practice. The lack of improvement in the baseline condition raises the concern that the “action” in these studies comes not from a benefit of action game training but from some unusual cost in the control condition.
- It is unclear how many independent findings of training benefits actually exist. Many of the papers touting the benefits of training for cognition only discuss the results of one or two outcome measures. It would be prohibitively expensive to do 30-50 hours of training with just one chance to find a benefit. In reality, such studies likely included many outcome measures but reported only a couple. If so, there's a legitimate possibility that the reported results reflect p-hacking. Those papers often note that participants also completed "unrelated experiments," but it's not clear what those are or whether they actually were the same experiment but different outcome measures. Based on the game scores noted in some of these papers, it appears that data from different outcome measures with some of the same trained subjects were reported in separate papers. That is, the groups of subjects tested in separate papers might have overlapped. If so, then the papers do not constitute independent tests of the benefits of gaming. If we don't know whether or not these separate papers constitute separate studies, any meta-analytic estimate of the the existence and effect size for game-training benefits is impossible. Together with the known failures to replicate training benefits and possible file drawer issues, it is unclear whether the accumulated evidence supports any claim of game training benefits at all.
Given that expert/novice studies tell us nothing about a causal benefit of video games for cognition and that the evidence for training benefits is mixed and uncertain, we should hesitate to promote game training as a cognitive elixir. In some ways, the case that video games can enhance the mind is the complement to recent fear mongering that the internet is making us stupid. In both cases, the claim is that technology is altering our abilities. And, in both cases, the claims seem to go well beyond the evidence. The cognitive training literature shows that we can enhance cognition, but the effects of practice tend to be narrowly limited to the tasks we practice (see Ball et al., 2002; Hertzog, Kramer, Wilson, & Lindenberger, 2009; Owens et al., 2010; Singley & Anderson, 1989; for examples and discussion). Practicing crossword puzzles will make you better at crossword puzzles, but it won’t help you recall your friend’s name when you meet him on the street. None of the gaming studies provide evidence that the benefits, to the extent that they exist at all, actually transfer to anything other than simple computer-based laboratory tasks.
If you enjoy playing video games, by all means do so. Just don’t view them as an all-purpose mind builder. There’s no reason to think that gaming will help your real world cognition any more than would just going for a walk. If you want to generalize your gaming prowess to real-world skills, you could always try your hand at paintball. Or, if you like Mario, you could spend some time as a plumber and turtle-stomper.
Other Sources Cited:
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