# Manipulating Stress Responses during Spaceflight Training with Virtual Stressors
## 6 Discussion
A possible explanation can be discerned from the increase in the high stressor anxiety levels. The attentional control theory [10] suggests that an increased environmental stressor resulted in more stress, less resources for emotion regulation, and thereby, increases in the perceived demand of the workload. Similarly, previous research that found heightened stress reactivity and threat sensitivity when individuals are in conditions with high amount of stress versus a lower threat sensitivity and reactivity in conditions with no stress [68]. The implications are that that anxiety can have adverse effects on processing efficiency and central executive capacity, thus, a subjective workload may increase concurrently with increasing stress levels, even when the task load stays constant. While VREs are a promising modality for training operations in stressful environments, questions still exist on how VRE designs effectively translate to the real world. The VR-ISS was created with focus on place illusion, plausibility, and virtual body ownership to enhance immersion and the potential to induce a stress response. However, a meta-analysis on stress biomarkers in VR by [69] found inconsistent responses across studies that induce a robust stress response with both high and low levels of immersion. Further, the individual difference may have a large impact on general biomarker responsivity; thus, new methods may be needed for induction to discriminate finer levels of stress. This study had several limitations that should be considered with regards to interpretation of results and future work. First, the sample size may have been small and statistically underpowered. Several of the measures (SBP, change in worry) had large effects sizes but marginally significant results, such that there is a possibility the effect exists when tested with more subjects. Running more participants would increase the statistical power and confidence in the results. Second, the study recruited participants from the general population rather than astronauts. The general population is less familiar with the ISS layout and procedures, which could possibly lead to stress or confusion from being trained in a short period of time. Further, astronauts may have stronger associations between threat cues and spaceflight hazards, and simultaneously, possible development of coping skills to manage the threat appraisal. Third, while Latin squares was used to minimize the influence of training order, statistical analysis to verify that assumption for six training-order sequences would be underpowered. Therefore, analysis of the counterbalance was not conducted, and it is unknown to the extent that the effects of the training-order influenced the differences among effects in the stressor levels [60]. Future work will include evaluating the simulations with a participant sample similar to the age range, education level, and demographic of astronauts. Future investigation of other training effects would be beneficial and include memory consolidation/retention, task performance, and physiological habituation over multiple sessions.