Psychophysiological Effects of Violent and Non-Violent Crowd Behavior Simulation in Immersive and Non-Immersive...

Understanding human reactions to violent incidents involving crowds is crucial for crowd management, evacuation, and emergency response. Unfortunately, studies involving real-world simulation of such scenarios are often infeasible due to ethical, practical, and safety constraints. Virtual reality is increasingly used to provide controlled simulation of such scenarios while preserving a degree of ecological validity. This work investigates how violent crowd behavior is experienced in an immersive virtual environment (iVE) and a non-immersive virtual environment (niVE). We conducted a user study with 74 participants in a virtual train station, manipulating crowd behavior (violent vs. non-violent) and virtual environment immersivity (iVE vs. niVE). We collected self-reported measures about emotional affect, sense of presence, social presence, and perceived realism of the crowd. Moreover, we recorded physiological indicators of stress and arousal (heart rate variability and electrodermal activity). Results showed that violent crowd behavior induced more negative emotional valence and lower perceived realism and sense of presence compared to non-violent crowd behavior, regardless of virtual environment immersivity. The effect of immersivity was significant for arousal, user involvement, and stress, as reflected in heart rate variability metrics (SDNN, HF, RMSSD). Overall, this work shows that despite niVE being sufficient to elicit self-reported emotional responses to violent crowd behavior, only iVEs can also trigger physiological emotional responses, which could be relevant in many applications such as crowd management training systems.