Another School Shooting: Consider the Weapons Effect


This time it was at Seattle Pacific University. On June 5, a 26-year-old man with a shotgun entered the school and started shooting. Reports indicated that four victims were brought to the hospital. As of now, one victim is dead, and the alleged shooter is in custody. The shooter was stopped by a student-hero with pepper spray.

Why did this man open fire in a school?

Most of us quickly focus on the shooter. He must be deranged or have an aggressive streak. Indeed, initial reports are suggesting as much.

But if we stop our thinking there, then we will be at risk of the fundamental attribution error or FAE. In the FAE, we quickly focus on personal characteristics and underestimate the possibility of situational factors.

I am in no way excusing the deadly attack (see Slogan #2 and my earlier post: Explaining Does Not Mean Excusing). Thank goodness the shooter was stopped as quickly as he was. But there might be additional external factors to help explain such deadly actions. Again, not excuses, but additional factors to help us understand mass shootings in America, so we might better prevent the next tragedy.

Since Sandy Hook, many who argue against gun control continue to comment that guns do not cause violence. People with mental health problems cause violence. This latest incident in Seattle will further fuel this belief. However, know that there can be multiple causes of extreme events. Even if mental health plays a major role in some shootings, so can other factors, including the presence of guns.

I am not trying to argue for or against more gun control. Balancing constitutional rights against scientific results about guns is difficult. It’s apples and oranges.

balance or scale

But the oranges are pretty easy to understand in this case. The presence of guns indeed contributes to violence, not only because guns are obviously the instruments in some violence but also through a little-known scientific finding called the “weapons effect” (Berkowitz & LePage, 1967).

The weapons effect shows that the visible presence of a weapon can cause an aggressive response. The trigger can pull the finger. Seeing a weapon prompts aggressive and hostile thoughts in the average person so that behavior becomes more aggressive, particularly if provoked. Perceiving provocation where none exists is also more likely if a weapon is present.

In Psychological Science, Craig Anderson and colleagues (1998) explained that the sight of a gun increases accessibility of aggressive thoughts, which can bring about aggressive behaviors in a variety of ways. Writings in Buddhist psychology might say that the sight of guns waters the seeds of our aggression. For example, in the presence of a gun, the average person may be more likely than when a gun is not present to interpret what is said as more hostile in tone than intended. The average person may also feel more justified in responding aggressively.

As of today, the weapons effect is well-replicated and has been found in both American and European samples, with children and adults, and in both laboratory and field settings (including while driving in traffic). It applies not only to guns but also to knives and pictures of weapons. So weapon-filled movies and video games would seem to apply.

I don’t know for a fact that the weapons effect was a factor in any of the recent mass shootings in America. But I’m using the weapons effect as one of many possible angles to talk about avoiding the FAE. Even when a terribly violent crime has been committed, the explanation is usually more complicated than to say an evil person committed an evil act. In particular, our culture of guns can contribute to our culture’s violence.

This reality does not excuse the perpetrators of violence on our streets or in our schools. This reality does not remove the rights of American citizens to bear arms. But better understanding this reality and better identifying broader causes of violence might ultimately help to reduce it.



Anderson, C. A., Benjamin, A. J., & Bartholow, B. D. (1998). Does the gun pull the trigger? Automatic priming effects of weapon pictures and weapon names. Psychological Science, 9, 308-314.

Berkowitz, L., & LePage, A. (1967). Weapons as aggression-eliciting stimuli. Journal of Personality and Social Psychology, 7, 202-207.


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