The purpose of this set of studies is to explore inattentional blindness in a naturalistic context. Specifically, we will study whether police trainees and officers fail to notice a gun in plain sight during various types of routine traffic stops. A number of studies show that experts can miss something unexpected if they are focused on other tasks. In most cases, though, the unexpected object is irrelevant and would not affect how they would perform their primary task. In this case, police trainees and officers will engage in a simulated traffic stop in which they know they will be ticketing a driver for failing to stop at a stop sign. A professional actor playing the role of the driver and will interact with the police officer as he or she approaches the stopped car. A gun will be placed in plain sight in the car. The primary measure is whether or not the officer notices the gun. Given that spotting a gun should lead to different actions by the officer engaged in a traffic stop, we have a direct measure of whether or not they saw the gun at the stop. If they failed to notice the gun, they will return to their car to write a ticket. If they notice the gun, they will ask the driver to exit the car and they will call for backup. Once they complete either of these actions, we will also use a funnel questioning procedure to determine what they noticed and when. A central question we will address in this project is whether a more stressful or threatening interaction will lead to more or less noticing of the gun. We will vary the induced threat by having the actor portray a compliant or hostile driver. By one view, the increased hostility should lead to greater situation awareness and search for threats, leading to more noticing of the gun. By another view, increased threat levels will lead police to focus more on the person and less on the situation, leading to less noticing of the gun. We also will eventually explore differences in noticing rates under these conditions by trainees and experienced officers.