## 2 Literature Review  
In this section, the literature review focuses on the latest state of immersive technologies and applications in PTSD-related psychotherapies. Publications from the American Psychological Association (APA), the Institute of Electrical and Electronics Engineers (IEEE) Xplore, and the Web of Science (WoS) digital library are searched using keywords Cognitive Behavior Therapy, Post Traumatic Stress Disorder, and Exposure Therapy. The results were further refined to include Virtual Reality Exposure Therapy and Driving Phobia. The two groups of literature are simply divided into VRET and traditional treatments. The traditional treatment types are further divided into CBT and ET. CBT and ET are commonly used to treat PTSD, depression, anxiety, and panic disorders. CBT reduces cognitive anxiety by letting patients understand the causes of their reactions and how to manage and change reactions that may exasperate their mental condition. The efficacy of CBT on anxiety-related mental disorders, especially PTSD, has been confirmed by many studies [7; 8; 9; 10]. Exposure therapy exposes patients to various levels of stimulating situations and continuously increases the intensity of the exposure to gradually induce a tolerance toward the exposure. Subjects are taught to self-analyze their reactions and change their behavioral response to better adapt to the changing conditions of exposure. Exposure therapy includes both imaginary and in vivo exposure. For imagined exposure, the therapist may ask the patient to imagine what they are afraid of. On the other hand, in vivo exposure allows patients to face the phobia directly. Some clinical trials have confirmed the effectiveness of exposure for treating PTSD. For example, [PERSON] et al. [11] divided 45 patients with PTSD into three groups--waiting list, exposure or counseling. The results showed that only 14% and 20% of the group members that received prolonged exposure and prolonged exposure plus anxiety management still suffered from symptoms of PTSD after treatment. Fifty-six percent of the supportive counseling group members were not affected by the PTSD treatment. The findings indicated that prolonged exposure may be a critical approach in the treatment of PTSD [11]. Aside from treating phobias, one of the successful applications of virtual reality technology is in the field of education. In one study, researchers have conducted a bibliometric study of the last twenty years from the Scopus database, and conclude that the use of virtual reality in education can improve the quality of the teaching and learning processes [12]. In [PERSON]'s research, he asserted that digital technology has become a part most of people's lives and entered various fields of society. For example, he applies VR to education and reports that VR yields many benefits such as optimizing teaching and learning processes, timely access to new information, greater mobility, ubiquitous access, and adaptable to the uniqueness of each student [13]. At present, there are many studies on the applications of VRET for various kinds of phobias such as acrophobia, arachnophobia, and aviophobia [14]. In one study, a 50-year-old officer who suffered from PTSD caused by the Vietnam War underwent VRET. After 14 treatments of up to 90 min over seven weeks, his PTSD symptoms fell 34% under standard clinical measures. Self-assessment decreased by more than 45% [15]. Another study of flying phobia ET confirmed that VRET and traditional ET have no difference in statistical effect size. Seventy-five patients with fear of flying (FOF) were divided into three groups (25 people in each group): VRET, traditional ET and the waitlist (do nothing). After treatment, the results of VRET and traditional ET were almost equivalent while both groups were superior to those on the waitlist [16]. Another study used meta-analysis to integrate effects from 21 clinical studies with a total of 300 subjects. The analysis results (effect size) demonstrated that VRET effectively reduces anxiety [17].