## 3 Discussion
### Supporting the Active Experience of Users Is Necessary  
Some of the researchers discussed in this review have taken the initiative to implement VR tools among people who do not present symptoms of PTSD, in order to assess their quality and ability to generate anxiety [8; 67]. For example, after active-duty soldiers in Iraq without PTSD tried the Virtual Iraq tool, they raised criticisms regarding the lack of realism [67]. In response, the authors added more avatars and vehicles to the environment. However, we believe that this level of realism could also be enhanced by developing components that would increase the subjects' levels of control through their interactions with the VE. Moreover, researchers have conceptualized contributing factors of presence in VE, categorizing them into four groups [26]: control factors, sensory factors, distraction factors, and realism factors. Control factors describe the mastery that the subject must have over the VE. Sensory factors relate to how information is presented through several sensory modalities and how the subject perceives that information. Distraction factors refer to interface awareness and the extent to which the user is isolated from the real world. Finally, realism factors are related to the naturalism of the VE and the relevance of the user experience. These categories align with those established by [PERSON] et al. [21] and [PERSON] [68], which highlighted sensory information, user control, and VE modifiability as essential for presence. This suggests, therefore, that if the subject interacts with the system using the same mechanics as those present in real life, they will likely experience a strong feeling of both perceived realism and presence in the exposure environment [13]. In other tests using the Virtual Iraq tool, participants suggested that patients should be allowed a gun, which they would be able to fire if necessary [67]. From this, we can infer that the subjects might have a deep desire to interact with the VE--either to defend themselves or to relieve the traumatic situation differently--and that it may be worth enabling patients to rectify errors they believe they committed during the actual traumatic event. This last possibility would be particularly interesting to explore for patients who have strong feelings of guilt connected to their traumas. Another point that we can garner from this review is the level of perceived boredom in VRET, as highlighted in [46]. In this study, the authors stated that the patient experienced boredom during the _in virtuo_ treatment and was subjected to in vivo experiences to resolve this boredom. We can, of course, partially reproduce a traumatic situation in real life for some cases of PTSD; nevertheless, this cannot be possible for all cases because of the myriad factors involved, including the nature of the situation and the anxiety level of the patient. Thus, if it is impossible to reproduce the scenario in vivo, one can only base the treatment and its results on _in virtuo_ sessions. As such, effective parameters for the design of VEs that favour adhesion and patient engagement, as well as allowing patients to invest in the VE as if it were reality, must be considered. Finally, although many existing VRET studies for PTSD have not focused on the interaction between subject and environment, some of them have reported behaviours reflecting the need for action that a patient may have in VRET situations [51]. A striking example was noted in a case study by [PERSON] et al. involving victims of African wars [51]: \"where cue intensity was raised, the participant assumed a combat position (arms and hands in a position such as if a firearm was being carried), trying to find the enemy within the scenario. When triggers such as ambush and mine deflagration occurred, the patient tried to take cover and started simulating firing.