Mickaël Causse

Startle and surprise, often resulting from sudden and unexpected events, have been implicated in numerous aviation accidents. To better understand this phenomenon, we investigated potential markers characterizing the reaction and individual differences in susceptibility. In total, 17 airline pilots took part in a flight simulator experiment, during which startling stimuli were administered (a loud thunder noise with a lightning flash) while behavioral reactions, flight performance, and physiological activity were recorded. Results showed that 92.3% of pilots exhibited an observable startle and surprise response, with flight performance degradation varying according to response intensity. The startling stimuli induced a significant increase in pupil diameter, and the subsequent flight performance was modulated by individual levels of neuroticism, highlighting the importance of personality factors in responses to unexpected events.

Objective: We aimed to characterize the impact of startle and surprise, both independently and in combination, on subjective feelings, behavior (task performance and gaze behavior), and several physiological parameters. Background: The effects of startle and surprise are known to affect pilots’ cognitive performance, with potential impact on safety. Startle and surprise can occur either together or independently, yet no studies have experimentally distinguished their specific effects. Method: Participants ( n = 45) were each assigned to one of the three conditions while performing the MATB-II task. In the startle condition, participants were subjected to an expected loud sound. In the surprise condition, an unexpected reverse video effect was applied to the experimental interface. In the combination condition, participants were exposed to both stimuli simultaneously. Results: Surprise was associated with an increase in skin conductance without affecting performance. In contrast, startle was marked by a decline in performance on the communication sub-task, increased skin conductance and heart rate, and a narrowing of attention. When startle and surprise were combined, the results mirrored those of startle alone but included a stronger feeling of startle and surprise, and a more prolonged heart rate increase. Conclusion: Startle and surprise combined yielded more numerous significant effects on subjective, behavioral, and physiological measures than startle and surprise independently. Application: Identifying the specific impacts of startle and surprise could pave the way for their automatic detection using artificial intelligence. Safety could be enhanced through the design of specific countermeasures to help the crew cope with such states.