Physiological sensations are reported by soldiers in relation to events that are only later found to be lifethreatening. Despite these anecdotal reports, the role of physiological responses in detecting threats has not been established. Physiological measures were recorded while experienced (recently returned from Afghanistan) and novice (no experience in Afghanistan) soldiers watched different types of video: walking or driving in neutral environments, and driving in Afghanistan. Participants were asked to identify nonthreatening and threatening situations by button presses according to the video watched. Analyses of eye movements revealed that experienced soldiers displayed smaller saccade amplitude, more fixations, and wider scanning patterns for the videos than novices. Analyses of heart rate variability indicated that physiological stress levels were higher for the experienced soldiers, particularly for the videos. The results suggest that experienced soldiers scanned their environment for threat more systematically than novices, and that this was associated with higher physiological arousal, suggesting a role for affective as well as cognitive processing of stimuli in expert threat detection. Language: en