The purpose of this study was to identify the strategies adopted by drivers when confronted to an unexpected event, pedestrian crossing, and to test the influence of having (or not) a collision with the pedestrian when faced to others pedestrian. Fifty-three participants were submitted to a simulator circuit including three unexpected pedestrians crossing the road. The subjective alertness and tension were collected by the Thayer questionnaire before the drive and the pupillary diameter was measured using an eye-tracking device. The results show that physiological state is important in the early processes of the driving session because it determines the first experience with an unexpected event and the change inherent to this experience. In a second time, driving parameters, such as speed and used strategy for avoidance, have a higher importance to explain driving performance.