## 6 Discussion
In virtual reality, we found that 15 studies in total proved the efficiency of using virtual reality in exposure therapy. Eight of the studies have not compared virtual reality exposure therapy to any other treatment methods [32]. Moreover, the other studies compare it to a different type of trial including in vivo treatment [39; 40; 41], remote therapy without the presence of the therapist [37], psychoeducation with an information pamphlet [38], and waitlist [21], which were all used to support the effectiveness of the virtual reality exposure therapy. Different types of specific phobias treated using virtual reality include animal phobias with various types of animals such as spiders [43], sharks [33], and snakes [24]. Moreover, there are situational phobias such as driving phobia [42] and flight phobia [45], natural phobias such as a height phobia [32], and blood-injection-injury phobia [40], which also includes dental phobias [14]. Figure 4: Types of specific phobias. Figure 5: Dominant technology in treating specific phobias. Furthermore, due to the significant degree of control that this technology provides, many experimental investigations have proved the utility of VR in testing theories linked to the processes and mechanisms involved in exposure therapy. Similarly, multiple research studies have demonstrated that virtual reality (VR) is an effective tool for studying critical elements associated to fear activation/reduction in the lab, as well as for generating helpful ideas for establishing novel treatment strategies to improve therapeutic outcomes. In augmented reality, there are only three studies that prove the potential and effectiveness of using augmented reality in exposure therapy to treat different types of specific phobias. One of the studies compares its effectiveness to in vivo exposure therapy [41], while the other two have not compared it to any treatment [35; 36]. However, these types include spider phobias [36] cockroach phobias [35] and both spider and cockroach phobias [41], which all are part of animal phobias. Moreover, one of the studies is a randomized controlled trial [41], while the other is a case study [35]. We noticed that augmented reality has been tested on only one type of specific phobia, animal phobia, which proves its ability for treatment efficiently. We would like to highlight the fact that most studies included information about the follow-up process after VR/AR exposure therapy sessions. For instance, ref. [49] discuss the short- and long-term efficacy of virtual reality (VR) exposure therapy for the treatment of flying phobia (FP). They present data from pre-treatment, post-treatment, and 1-year follow-up assessments in a sample of nine participants using a multiple baseline design. The results obtained at post-treatment and 1 year after the completion of the treatment support the efficacy of VR in the treatment of flying phobia. Moreover, several studies with larger samples report evidence of the maintenance of treatment for a long-term period [50]. Overall, the studies included were mostly randomized controlled trials that were tested on adults more than 18 years old from both genders that must have the tested phobia. In addition, the treatment sessions' numbers vary based on the increased difficulty and realism of the 3D models used. Additionally, a number of the studies did a follow-up to check the treatment efficiency. VRET/ARET applications have evolved into a viable alternative that, in terms of efficacy, can meet the results of traditional phobia treatments. They are, nevertheless, tools that can be used to improve the field of psychiatric treatment. There will be a major increase in the routine usage of these VRET/ARET applications in clinical settings in the future years, but there are significant difficulties to overcome first. The acceptability of these technologies by clinicians is the most significant factor.