Expertise modulates visual sampling strategies in authorised firearms police officers

High-risk incidents require responders to rapidly detect, sample, and interpret critical visual information. To understand how experience shapes these abilities, we used mobile eye-tracking to examine expertise-related differences in gaze behaviour of Authorised Firearms Officers during simulated tactical scenarios. Receiver operating characteristic analysis revealed that the number, duration, and horizontal spread of fixations moderately discriminated between expert and novice officers, with experts tending to perform more, but shorter fixations that were distributed more broadly. Experts also exhibited greater consistency in gaze location even when suspects were hidden from sight, suggesting they shared expectations about where threats may emerge. In the moments leading up to operational responses, experts increased their fixation durations, indicating more deliberate visual preparation. We also evaluated which visual features best explained fixation locations. A model combining low-level saliency with a focus on suspects' waistlines provided the most accurate account of officers' gaze patterns.