Effects of Weapons on Aggressive Thoughts, Angry Feelings, Hostile Appraisals, and Aggressive Behavior: A Meta-Analytic Review of the Weapons Effect Literature

Abstract

A landmark 1967 study showed that simply seeing a gun can increase aggression-called the "weapons effect." Since 1967, many other studies have attempted to replicate and explain the weapons effect. This meta-analysis integrates the findings of weapons effect studies conducted from 1967 to 2017 and uses the General Aggression Model (GAM) to explain the weapons effect. It includes 151 effect-size estimates from 78 independent studies involving 7,668 participants. As predicted by the GAM, our naïve meta-analytic results indicate that the mere presence of weapons increased aggressive thoughts, hostile appraisals, and aggression, suggesting a cognitive route from weapons to aggression. Weapons did not significantly increase angry feelings. Yet, a comprehensive sensitivity analysis indicated that not all naïve mean estimates were robust to the presence of publication bias. In general, these results suggest that the published literature tends to overestimate the weapons effect for some outcomes and moderators.

The Weapons Effect

“…A recent meta-analysis suggests that weapons reliably prime aggressive thoughts (Benjamin et al, 2018). The initial mean effect size was small-to-moderate.…”

“…After Carlson et al (1990) published their meta-analysis, research on the influence of weapons on aggressive behavioral outcomes largely ceased, with exceptions duly noted (e.g., Bushman, Kerwin, Whitlock, & Weisenberger, 2017;Guo, Egan, & Zhang, 2016;Klinesmith et al, 2006;and Lindsay & Anderson, 2000). A more recent meta-analysis including all known available published and unpublished research on the weapons effect suggests that the influence of weapons on aggressive behavior is inconclusive for now (Benjamin, Kepes, & Bushman, 2018). Although the weapons effect appears to be statistically reliable on the surface, once publication bias and outlier effects are taken into consideration, it is not entirely clear what the "true" mean effect size for the influence of weapons on aggressive behavior actually is.…”

“…The mean effect size may be small but reliable if a random effects trimand-fill analysis is used to estimate publication bias, but other techniques to estimate publication bias show an average effect size close to zero. As a result, Benjamin et al (2018) suggest caution in interpreting research on the influence of weapons on aggressive behavioral outcomes.…”

“…When examining the influence of weapons on aggressive appraisals, Benjamin et al (2018) found that the average effect size was approximately moderate. Once primed, individuals appear biased to make initial appraisals of threat and secondary appraisals of hostility.…”

“…That said, even taking into consideration publication bias, the magnitude of the average effect remained statistically reliable. (Benjamin et al, 2018).…”