Eyewitness Identification and the Weapon Focus Effect: Effects of Weapon Presence and Concealment

Document Type


Degree Name

Master of Science (MS)


Psychology and Special Education

Date of Award

Fall 2015


The purpose of this study was to investigate certain boundary conditions for the weapon focus effect (WFE). Specifically, we sought to determine whether or not a concealed weapon also produces such an effect, which is important based on the large number of crimes in which a perpetrator refers to a concealed weapon but does not openly brandish it. It would be of interest to police to know whether eyewitnesses’ attention might be drawn to the concealed weapon (e.g., bulge in the jacket pocket) similarly to a visible weapon, thereby reducing their ability to make an accurate lineup decision later. The experiment featured a mock crime video in which a perpetrator either had no weapon, a visible weapon, or referred to a concealed weapon in his pocket. Shortly after viewing the video, participants were faced with an identification decision from a lineup that either contained the perpetrator or not. The identification decisions as well as the confidence in those decisions were analyzed in order to determine the existence of the WFE across conditions. There were two primary findings. First, the WFE was replicated, such that when the perpetrator openly showed the weapon throughout the crime, participants were much worse at discriminating between guilty and innocent suspects. Second, and of greater interest, there was no difference in discriminability between the weapon concealed and no weapon conditions. Both performed much better than the weapon presented condition. Apparently no WFE occurs with a concealed weapon, even when a perpetrator refers to the weapon in his pocket. This has important implications for police and the criminal justice system.


Curt Carlson

Subject Categories

Psychology | Social and Behavioral Sciences