Expert: Holding a gun changes the way people perceive others, objects

March 26, 2012

WEST LAFAYETTE, Ind. - Just the act of holding a gun affects a person's perception in a way that makes them more likely to incorrectly perceive others holding weapons that aren't really there, says a Purdue University perception expert.

"There are many examples of an unarmed person being shot because it was believed they were holding a weapon," says Jessica K. Witt, an assistant professor of psychological sciences. "We wanted to approach the role perception plays in these scenarios, because perception goes beyond just what a person sees, and awareness of this change in perception could keep people from getting hurt.

"We hope that this information will be helpful to anyone who relies on a firearm for self-defense."

Witt and James R. Brockmole, an associate professor of psychology at the University of Notre Dame, tested how holding a gun influences a person's ability to identify an obscure object being held by another person in a series of five experiments. The findings will be published in an upcoming issue of Journal of Experimental Psychology. They evaluated when study participants, who were not regular gun users, believed others were holding guns and how quickly they reacted to that perception. The researchers found those holding a gun were more likely to report a gun present compared to those not holding a gun, and they also reported it as a gun more quickly.

The situations in the computer images varied across experiments to show some people holding the object to the side or directly at the camera. Other variations included images of people of different races or some people wearing ski masks. Witt will next be looking at similar studies to evaluate perception and gun bias with people who are trained to use guns.

"When someone holds a gun they become a shooter, and this changes how that person perceives other people and things," Witt says. "This starts with what the gun is doing to a person as it is held or used because as a shooter, your perceptual systems align with seeing yourself as a shooter. We've seen in other studies how action can influence perception, such as when softball players or golfers have better batting averages or scores they see their target as larger."

The study also looked at race, but found that there was not a bias.

"However, there are other factors related to race, and that is where stereotypes come in," she says. "If you have stereotypes, and your perception is changed when holding a gun, those factors could interact to increase the likelihood of an overreaction. In our study, there was a gun in 50 percent of the trials. In the real word that is not typically the case, but I would expect in the real world, this gun effect and race stereotype could amplify each other."

Her work is supported by the National Science Foundation.

Writer: Amy Patterson Neubert, 765-494-9723,  

Source: Jessica K. Witt, 765-496-1916,

Related websites:
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Note to Journalists:
Journalists interested in a copy of the journal article can contact Amy Patterson Neubert, Purdue News Service, at 765-494-9723,



Action Alters Object Identification: Wielding a Gun Increases the Bias to See Guns

Jessica K. Witt and James R. Brockmole

Stereotypes, expectations, and emotions influence an observer's ability to detect and categorize objects as guns. In light of recent work in action-perception interactions, however, there is another, unexplored factor that may be critical: The action choices available to the perceiver. In five experiments, participants determined whether another person was holding a gun or a neutral object. Critically, the participant did this while holding and responding with either a gun or a neutral object. Responding with a gun biased observers to report "gun present" more than did responding with a ball. Thus, by virtue of affording a perceiver the opportunity to use a gun, he or she was more likely to classify objects in a scene as a gun and, as a result, to engage in threat-induced behavior (raising a firearm to shoot). In addition to theoretical implications for event perception and object identification, these findings have practical implications for law enforcement and public safety.