# Intelligent Virtual Reality and Augmented Reality Technologies: An Overview
## 2 Materials and Methods
### Systematic Literature Review Process  
Taking the findings of recent studies [66; 67] into account, Scopus and Web of Science were selected as the main data sources to identify studies relevant to the topic due to their being highly regarded, containing impactful documents, and being used in other literature review and bibliometric analysis studies. Another reason for the selection of these databases was the ability to use the extracted information with the aforementioned tools [61; 62].  
Moreover, different combinations of keywords were tested to ensure that the most relevant documents were identified. The final query defined and used was the following: (\"augmented reality\" OR \"AR\" OR \"virtual reality\" OR \"VR\" OR \"mixed reality\" OR \"MR\" OR \"extended reality\" OR \"XR\" OR \"metaverse\") AND (\"artificial intelligence\" or \"AI\"). It should be noted that although the abbreviations might identify some documents that are not relevant (e.g., MR can also be magnetic resonance, etc.), it was deemed appropriate for them to be used to avoid missing any potentially relevant documents. As a result, during the initial screening process, several documents were deemed to be out of scope. Additionally, as the aim of this study was to provide an overview of the topic, specialized keywords that could restrict the search to specific domains or provide explicit directions were not used. In this sense, the document collection would contain a larger number of documents but would also sufficiently provide a general representation of the current literature.  
The final search for relevant documents using the aforementioned query was conducted on Scopus and Web of Science in December 2024 to identify suitable studies based on their title and abstract. In this study, only documents written in English were included. Additionally, to ensure that the most up-to-date research is being reported, the analysis involves studies that were published in the last decade, that is, 2015-2024. Following the guidelines specified within the PRISMA framework, the steps taken to search, identify, and process the related documents are presented in Figure 1.  
Initially, the document collection comprised 12,281 documents with 7983 documents retrieved through Scopus and 4298 retrieved through Web of Science. The documents were then examined to identify duplicate documents using automatic and manual approaches. In total, 3533 duplicate documents were identified and removed from the document collection. As a result, the document collection consisted of 8748 documents before the initial screening which was on the existence of keywords within the title and abstract of the documents. Additionally, in order for a study to be included in the analysis, the inclusion criterion that had to be met was for it to directly focus on AI and VR and/or AR or on their combination from a theoretical or experimental perspective. Hence, studies that focused on one of these technologies or simply mentioned these terms but did not focus on their use or combination were excluded. From this process, a total of 7651 documents were removed. The remaining 1097 documents were manually examined to determine their suitability. Specifically, 65 documents were removed as they were outside the scope of this study, 41 documents were removed since they were letters, notes, and abstracts only, 38 because they were editorials, 28 because they were proceedings, 27 because they were retracted documents, 10 because they were books, 5 because they were book reviews, and finally, 3 documents were removed because they were erratum/corrections. Consequently, a total of 880 documents were included and analyzed in this study.