Overstated Evidence for Short-Term Effects of Violent Games on Affect and Behavior: A Reanalysis of Anderson et al. (2010)
Violent video games are theorized to be a significant cause of aggressive thoughts, feelings, and behaviors. Important evidence for this claim comes from a large meta-analysis by Anderson and colleagues (2010), who found effects of violent games in experimental, cross-sectional, and longitudinal research. In that meta-analysis, the authors argued that there is little publication or analytic bias in the literature, an argument supported by their use of the trim-and-fill procedure. In the present manuscript, we reexamine their meta-analysis using a wider array of techniques for detecting bias and adjusting effect sizes. Our conclusions differ from those of Anderson and colleagues in 3 salient ways. First, we detect substantial publication bias in experimental research on the effects of violent games on aggressive affect and aggressive behavior. Second, after adjustment for bias, the effects of violent games on aggressive behavior in experimental research are estimated as being very small, and estimates of effects on aggressive affect are much reduced. In contrast, the cross-sectional literature finds correlations that appear largely unbiased. Third, experiments meeting the original authors’ criteria for methodological quality do not yield larger adjusted effects than other experiments, but instead yield larger indications of bias, indicating that perhaps they were selected for significance. We outline future directions for stronger experimental research. The results indicate the need for an open, transparent, and preregistered research process to test the existence of the basic phenomenon.