**Protocol - Experienced Officers** ------------------------------------------------------------------------ **The effects of tension level during a traffic stop on noticing of a conspicuous threat (a gun)** ---------- Except as noted, this protocol is identical in all respects to the registered protocol for Study 1 ([https://osf.io/pcbfj/wiki/home/][1]) that tested recruits at the Police Training Institute. The protocol differs in the following ways: 1. The participants will be experienced police officers who are returning to the Police Training Institute for half-day or full-day refresher courses on traffic stops. They are also returning to provide feedback to the Police Training Institute on its training procedures. They will not be paid for their participation in the study, but they are still paid by their home department for their time at the Institute (they are still paid and are still on duty for this refresher course). 2. Rather than a regular multi-week session, the officers are visiting the institute for just one day. The Institute has scheduled 3 half days with approximately 15-20 police officers attending each. We will schedule an additional half day or full day sessions with up approximately 50 officers on future dates. 3. We will test as many of the officers as possible during each of the three half-day sessions. If we have usable data from at least 40 participants in each condition at the end of testing, we will end data collection. If we still need additional participants, we will schedule additional sessions with experienced officers. We will continue adding testing sessions until, at the end of a testing session, we have at least 40 participants in each condition. (Note that we will test as many participants as possible in any scheduled session, so we may have more than 40 participants in one or both conditions by the time we complete testing in the final session). 4. We will use the same random order of testing that we used in the study with recruits (see the pre-registration for that study to see the order). 5. Note that we will begin testing the officers while the study with recruits is ongoing, but testing will be on different days. **All other aspects of the procedure are identical to those in our pre-registration of the procedures for testing recruits ([https://osf.io/pcbfj/wiki/home/][2]).** [1]: https://osf.io/pcbfj/wiki/home/ [2]: https://osf.io/pcbfj/wiki/home/