The weapons effect is a phenomenon described and evidenced for in the scientific field of social psychology. It refers to the mere presence of a weapon or a picture of a weapon leading to more aggressive behavior in humans, particularly if these humans are already aroused.[1] This should not be confused with the weapon focus, another social psychology finding. This effect was first described by Leonard Berkowitz and Anthony LePage in 1967 in their paper "Weapons as Aggressions-Eliciting Stimuli" in the Journal of Personality and Social Psychology. The paper outlines an experiment conducted by the authors at the University of Wisconsin. The researchers tested their hypothesis that stimuli commonly associated with aggression (like weapons) can elicit more aggressive responses from people "ready to act" aggressively.[2]

It is important to note that several psychology researchers have also criticized the weapons effect, questioning the original research study’s findings. This is because subsequent studies have been less successful at replicating the weapons effect, and alternative explanations have been proposed. For example, more recent research has proposed that there are more factors that influence aggression in a situation containing a weapon, such as an individual's familiarity with the weapons present.[3]

As work with the weapons effect progressed, researchers also demonstrated the weapons priming effect. This variation refers to even weapon-related words leading to more aggressive behavior in humans.