No Pain, No Gain? The Effects of Adding a Pain Stimulus in Virtual Training for Police Officers 4 89 validity were affected by the addition of a pain stimulus. One reason why the addition of a pain stimulus may not have influenced the sense of presence is that a nociceptive stimulus provides information about the body itself (i.e. interoceptive function) rather than information about the environment, as auditory and visual stimuli do (i.e. exteroceptive function; Craig, 2002; Ogden et al., 2015). Thus, while the virtual environment is primarily experienced through exteroceptive senses like auditory and visual experiences, adding a stimulus like pain that is experienced interoceptively may not influence the sense of presence (i.e. the feeling of fully being there in the virtual environment) as much as exteroceptive stimuli would. Taken together, a pain stimulus may not be the most relevant sensory stimulus to add to the virtual environment to enhance the sense of presence, as it provides limited information about the environment itself. It should, however, be considered that the possibility of getting hit by an opponent appears to influence the behavioural responses of police officers, such as adjusting their posture to make themselves smaller to avoid getting hit (Nieuwenhuys & Oudejans, 2010). Therefore, while the pain stimulus may not have influenced the feeling of ‘being there’ in the virtual environment, it may have influenced how police officers reacted to the virtual environment on a behavioural level. These behavioural responses may also give an indication of how present someone feels in the virtual environment because realistic behavioural responses are more likely to occur when presence is high (Slater, 2009). Whilst not explored in this study, the addition of a pain stimulus to virtual training simulators may support eliciting duty-like behavioural responses. Future studies in VR should therefore explore the influence of a pain stimulus on behavioural responses and in conjunction with presence. To conclude, hypothesis 2 is not supported by our data—the addition of pain stimulus to virtual training simulators did not influence the sense of presence in the virtual environment. This may also be due to a ceiling effect as the sense of presence (spatial presence, engagement, ecological validity) was relatively high in both simulators. In addition to investigating the influence of a pain stimulus on the training responses and sense of presence in virtual training simulators, our analysis also revealed differences in training responses between the two training simulators. When looking at the physical training responses between the simulators, VR provoked significantly higher average HR and max HR compared to VirTra. This difference is likely explained by the inherent lack of similarity of the training simulators: VR training offers the greater possibility for movement as trainees have more space to move about. Additionally, in VR, trainees wear VR gear that adds an increased physical load, thus, increasing cardiovascular responses to the VR training compared to the VirTra in which trainees do not have any additional gear. Further, differences in sense of presence between the simulators exist as well: police officers experienced more spatial presence in VR, while also experiencing more negative effects compared to VirTra. These findings indicate that the training
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