Abstract
Attentional states, beliefs, expectations, and emotions influence an observer's ability to detect and categorize objects. In light of recent work in action-specific perception, however, there is another, unexplored, factor that may be critical in object identification: The action choices available to the perceiver. According to the action-specific account of perception, people perceive their environment in terms of their ability to perform an action. Individual variability in body type, performance skill, and intended behavior all scale optical information when making perceptual judgments. To determine if this scaling extends to the identification of objects, we asked whether people holding guns adopt different criteria to classify objects as threatening or nonthreatening. Across multiple experiments, participants determined whether another person was holding a gun or a neutral object such as a wallet. Critically, the participant did this while holding either a gun or a ball. Participants were instructed to raise their held object, as quickly and accurately as possible, if they detected a gun, and to lower their held object in the absence of such a threat. Signal detection analyses showed that holding a gun biased observers to report “gun present” while holding a ball biased observers to report “gun absent.” Thus, by virtue of affording a perceiver the opportunity to use a gun, he or she is more likely to classify objects in a scene as threats and, as a result, to engage in threat-induced behavior (in this case raising a firearm to shoot). These findings provide empirical credence to the familiar saying that when you hold a hammer everything looks like a nail. But, in this case, when you hold a gun, everything looks like a target. In addition to theoretical implications for event perception, object identification, and decision making, these findings have practical implications for law enforcement and public safety.