1. Introduction
Artificial intelligence (AI) is rapidly advancing as a field of study and due to its wide applicability and potentials, it is rapidly being integrated into different domains. AI refers to smart systems that simulate human intelligence and mimic the way they think, communicate, and act [
1,
2,
3] as the development of these systems is driven by the human nervous system and humans’ innate ability to learn, adapt, and reason [
4,
5,
6]. Through the use of AI, intelligent systems [
7,
8,
9], virtual agents and assistants [
10,
11,
12], and multi-agent systems [
13,
14,
15] can be created. Recent literature review studies have explored its use in various domains, such as education [
16,
17,
18], industry [
19,
20,
21], healthcare [
22,
23,
24], business [
25,
26,
27], smart cities [
28,
29,
30], etc. The outcomes of these studies highlight the potential of AI to transform and enrich various sectors, which, in turn, reveals the need to further explore its capabilities to be used in combination with other novel technologies to further amplify its impact.
Immersive technologies can be greatly influenced and improved through the integration of AI. Recent studies have highlighted the benefits that this combination can potentially yield [
10,
11,
31,
32]. Specifically, emphasis is being placed on the use of AI within augmented reality (AR), virtual reality (VR), and mixed reality (MR) environments. AR focuses on embedding interactive digital information and content in users’ physical environment [
33,
34] and is closer to the real world in the “reality-virtuality continuum” [
35] while VR focuses on virtual environments that fully engulf and immerse users [
36,
37,
38], thus separating them from the real environment and, as a result, it is closer to the virtual environment in the continuum. Additionally, the metaverse, which is characterized by its realistic virtual experiences and environments that constitute an extension of the real environment [
39,
40,
41], is closely related to XR technologies and the creation of virtual worlds and environments with high levels of embodiment, interactivity, and persistence [
42,
43]. As these technologies create new ways for users to interact, communicate, and experience events, they are increasingly being used in various settings and domains including education [
44,
45,
46,
47], industry [
48,
49,
50], healthcare [
51,
52,
53], business [
54,
55,
56], smart cities [
57,
58,
59]. The studies highlighted the role of VR and AR in each domain and the benefits they can yield. The domains, although indicative, were selected to highlight the similarities in terms of application domains among AI, AR, and VR.
The outcomes of the recent studies have revealed the positive impact that they can have in different domains. Hence, studies have also started to examine their combined use. However, although these technologies constitute established fields of studies on their own, their inter-relationship has yet to be examined in detail. As a result, there has not been any study that has examined the current state of the art regarding the use of AI within VR and AR environments and the metaverse. Examining the use of AI within extended reality (XR) environments can bring about new use cases as well as new opportunities. Additionally, by integrating AI, user-tracking, monitoring, and data processing can be improved and content and activities recommendation can be enhanced. Through this approach, more adaptive and personalized experiences, unique to each individual, can be created within immersive and interactive environments. Hence, it is vital to examine the convergence of these technologies. As this field of study is advancing, it is important to have a representation and mapping of the existing literature to identify emerging thematic areas and topics, limitations and challenges, and future research areas. Therefore, to bridge this gap, the aim of this study is to provide an overview and mapping of the existing literature about the convergence of AI with VR and AR technologies as well as to reveal future research directions. The main contributions of this study are the in-depth analysis of the document characteristics, the definition of the more advanced research domains and of the emerging ones, the identification of the most widely explored topics, themes, and trends, and the provision of future research areas while considering the challenges presented in the literature. To provide a thorough, valid, and reproducible analysis, the study follows the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) [
60] framework to report the document identification, processing, and selection and utilized widely accepted tools and approaches, such as Bibliometrix [
61], VOSviewer [
62], and topic modeling through Latent Dirichlet Allocation (LDA) [
63]. The study structure is as follows: the main methods and materials used are presented in
Section 2. The analysis of the document collection is presented in
Section 3 and in
Section 4, the findings are further discussed and summarized. In
Section 5, the conclusions of this study are presented, the implications are highlighted, the limitations are detailed, and future research directions are suggested.
2. Materials and Methods
As the study strives to explore the use of AI and XR technologies from a general perspective without being limited to a specific domain, a bibliometric analysis, scientific mapping, and content analysis approach was followed to present the state of the art. This approach is deemed suitable to examine similar topics with broad reach [
64]. Moreover, to ensure an accurate, valid, and reproducible analysis of the literature, the study followed the PRISMA statement [
60] as well as clearly defined guidelines presented in the literature [
61,
65].
Furthermore, the study used different approaches and tools to analyze the related studies. Specifically, the open-source tool Bibliometrix along with the related method defined by Aria and Cuccurullo [
61] were used to carry out the bibliometric and scientific mapping of the literature. To further examine the related documents and their networks, VOSviewer was also used [
62]. To identify the most prominent topics discussed within the document, topic modeling through the use of LDA [
63] was conducted. The tools used are being widely adopted by similar studies which highlights their suitability and effectiveness. Additionally, the use of different tools and approaches enabled a more thorough representation of the state of the art.
2.1. 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.
4. Discussion
AI as well as VR and AR are increasingly being used in different sectors, yielding significant benefits and transforming them. XR technologies offer immersive, engaging, and interactive experiences [
47,
69,
70]. However, these experiences should be carefully designed following appropriate guidelines and principles [
71,
72,
73,
74,
75,
76]. Studies have explored the use of AR and VR in different domains and use cases while reporting positive outcomes [
77,
78]. Simultaneously, AI is rapidly advancing and it is being integrated into various domains and aspects of everyday life [
79,
80]. Due to their nature and capabilities, these technologies can complement and enrich each other both in terms of functionality and capabilities [
32].
This study focused on examining the existing literature to identify the role and integration of AI within VR and AR environments. Specifically, the study analyzed 880 documents relevant documents that were identified following the PRISMA guidelines. The related data was analyzed using content analysis, bibliometric analysis, and scientific mapping techniques. Additionally, the data is further explored through LDA as shown below. The documents had a significantly high annual growth rate (91.29%) and an average document age of 1.36 years highlighting the recency of the topic and the increased interest in further advancing this field of study. Additionally, the documents examined were written by 2938 authors and published in 622 different sources during the time period 2015–2024. Most documents were published as conference/proceedings papers, followed by journal articles. Additionally, the documents on average had 4.1 co-authors and an international co-authorship rate of 15.0%; thus, highlighting the multidisciplinary nature of the field and the need for global collaboration to further advance it.
Furthermore, most documents were published in the last three years with 2024 being the year with the most published documents, followed by 2023 and 2022. Based on the number of published documents, the 10-year time period examined was divided into three separate periods: 2015–2018: Initial conceptualization; 2019–2021: Materialization; and 2022–2024: Breakthrough. Additionally, the documents which received the highest mean total citations were published in 2019, 2022, and 2021, although this outcome is expected to change given the rapid development of the field and the increase in the number of new documents published. The sources in which the documents were published were categorized into three clusters following Bradford’s law and also analyzed based on their h-index. According to the related outcomes, the most relevant sources were identified.
Moreover, using Lotka’s law, the distribution of the written documents which the authors have contributed to is presented. Despite the vast majority having participated in a single document, there are authors who are actively pursuing this novel field of study and it is expected that these outcomes will also change in the near future. The authors were from 71 different countries across the globe and countries from different continents ranked among the top in terms of scientific production in the field. Similarly, the author affiliations were examined. The related outcomes highlighted the most productive and relevant countries. The development of international collaborations, which were categorized into six clusters, further highlight the diverse and complicated nature of the field and the need to examine it from multiple perspectives and incorporate the insights of authors from various backgrounds and expertise.
By examining both author’s keywords and keywords plus (indexed keywords) of the documents, the thematic areas and main topics covered were examined. The results revealed the close relationship of AI, AR, and VR with the field of education and healthcare and also highlighted their inter-relation and their close relationship with other novel technologies. Particular emphasis was also put on human-computer interaction and the application of machine learning and deep learning. To better comprehend these topics, LDA, which is a probabilistic Bayesian model with a three-level hierarchical structure [
63], was also used to identify topics within the document collection based on the title and abstract of the documents. Hence, using LDA, the following general topics and categories of interest emerged: “Education/Learning/Training”, “Healthcare and Medicine”, “Generative artificial intelligence/Large language models”, “Virtual worlds/Virtual avatars/Virtual assistants”, “Human-computer interaction”, “Machine learning/Deep learning/Neural networks”, “Communication networks”, “Industry”, “Manufacturing”, “E-commerce”, “Entertainment”, “Smart cities”, and “New technologies” (e.g., digital twins, blockchain, internet of things, etc.). These outcomes are in line with the results of the keywords and trends analysis and further validate the topics/areas identified.
Furthermore, focusing on the total citations received within the document collection, the top documents relevant to the topic that explore the use of AI along with VR and/or AR were identified. The related outcomes are presented in
Table 14 and are analyzed to provide an overview of the most impactful studies that currently guide this field of study.
Hwan and Chien [
81] explored the metaverse through the lenses of AI. Their study went over the potential research issues, role, and definition of the metaverse and the role of AI within the metaverse. The study highlighted the potentials of the AI-enriched metaverse to support and improve the educational process. Additionally, it offered future research topics and directions and commented upon the wider use of the metaverse in the near future. Wen et al. [
82] focused on VR space and the use of AI to improve sign language recognition to enable bidirectional communication using haptic devices. In their study, they used a deep learning model for the recognition and translation of the sign language. Their outcomes revealed the significant benefits that can be yielded when integrating AI within VR environments to improve everyday life and communication. Zhang et al. [
83] focused on the transition from AR and VR to the realization of digital twins using AI sensing technologies in the context of the internet of things. The study commented upon the role of AR, VR, and digital twins and highlighted the ability of using AI to design effective intelligent sensor systems. Finally, they pointed out the ability of AI to optimize processes and improve automation and of the metaverse and digital twins to bring about new opportunities for achieving a smarter future and commented on the existing challenges.
In another study, Yang et al. [
84] examined the combination of AI and blockchain with the metaverse. The study focused on the unique characteristics and aspects of the metaverse and how they can be enhanced by using AI. The study also went over the use of blockchain and its applicability within the metaverse. Moreover, it presented key challenges and open issues related to digital economies, technological limitations, governance, regulations, as well as security and privacy. Finally, the study highlighted the important role that both AI and blockchain will play in the creation of an ever-expanding metaverse. Huynh-The et al. [
85] carried out an in-depth survey regarding the use of AI within the metaverse. The study went over the categorization of the different AI types, its role in the metaverse, as well as the technical aspects in which its integration can aid with, such as natural language processing, computer vision, blockchain, digital twins, neural interfaces, and networking. Additionally, it explored various application domains, such as healthcare, manufacturing, smart cities, and gaming while also commenting on its potential use in e-commerce, real estate, and decentralized finance.
Chen et al. [
86] explored the integration of AI within AR microscopes for cancer diagnosis. The study focused on presenting the proposed platform which capitalizes on AR for effective representation and interactivity and on AI for identification. Overall, the study highlights the potential that the combination of these technologies can yield in the field of healthcare. Mozumder et al. [
87] provided an overview regarding the future trends of the metaverse focusing on AI, internet of things, and blockchain. Their work focused on the medical domain and commented upon the virtual environments and worlds that can be created within the metaverse. Additionally, the study highlighted the technologies which the metaverse uses and explored AI use cases within the metaverse as well as the use of the metaverse in healthcare. Winkler-Schwartz et al. [
88] focused on VR simulations in the context of assessing surgical expertise. Their approach emphasized machine learning and the role of AI in medical education. Specifically, they looked into how machine learning can be used in the context of VR simulations to evaluate users’ performances. The study also provides a general framework to effectively report and analyze studies that focus on machine learning and VR surgical simulations.
Sahu et al. [
89] carried out a review regarding the use of AI within AR applications targeted at manufacturing. The study highlighted the benefits that AR can bring about and how AI can be used to further enrich AR applications. Specifically, the study focused on identifying the main concepts and the limitations of the existing methods and explored various AI-based approaches that could help address these challenges. The study also commented upon the benefits of AI in manufacturing and within AR-based applications. Chang et al. [
90] explored 6G-enabled edge AI for the metaverse. Specifically, the study presented the main aspects of the metaverse and focused on the existing challenges that it faced. Additionally, the study looked into the limitations specified in the existing literature and provided future research directions. Holstein et al. [
91] examined a mixed reality teacher awareness tool in the context of AI-enhanced classrooms. Specifically, the study focused on intelligent tutoring systems and advanced analytics which were displayed in an MR headset. Their study revealed that the use of MR-based teacher analytics can help address the learning outcome gaps observed among students of different levels of knowledge and skills. Finally, the outcomes of the study highlighted the benefits that the AI systems can bring in education and the potential that the combination of integrating human and machine intelligence can have in supporting students’ learning.
The outcomes of the aforementioned studies reveal the potentials of integrating AI within AR and VR environments as well as the metaverse across different contexts. Moreover, they highlight the need to integrate and combine new technologies to meet the emerging requirements. Based on the scope of the studies, it can be inferred that emphasis is being placed on the role of AI within the metaverse as well as within XR environments in the education and healthcare domains. The sections and topics covered in the aforementioned studies are in line with the topics and areas identified within this study. Additionally, the gradual evolution and shift of focus is also in line with the thematic evolution presented in this study. Hence, the results of this study further validate those of the previous literature regarding the potentials of combining AI with XR technologies and the metaverse and highlights its ability to be effectively integrated into different domains.
However, it should be noted that there are several open challenges and barriers that need to be addressed before these technologies are more widely adopted and applied. These barriers involve privacy and security issues, ethical concerns, technical and computational limitations, algorithmic bias considerations, software and hardware limitations, sustainability and interoperability considerations, as well as development and adoption hurdles [
41,
92,
93,
94,
95]. As these challenges exist for AI, the metaverse, and XR technologies, emphasis should be placed on exploring them through the lenses of each individual technology as well as of their combined use.
5. Conclusions
XR technologies are rapidly advancing and being integrated into various domains. Specifically, the adoption and use of AR and VR have brought about several benefits and new opportunities to different sectors including education, healthcare, industry, etc. Simultaneously, due to the recent advances, AI is also gaining ground and being integrated into several domains reinforcing them and enriching them. These technologies can be combined to yield even greater outcomes; hence, the research into this topic is rapidly increasing. This study aimed to provide an overview through the examination, analysis, and mapping of the existing literature regarding the use of AI within AR, VR, and the metaverse.
To provide a thorough overview, the study followed the PRISMA guidelines and used different analysis methods and tools. Specifically, the study focused on carrying out a bibliometric analysis, scientific mapping, content analysis, and topic modeling of the related literature. In total, the study examined 880 documents which were identified from Scopus and Web of Science and were published during 2015–2024. The study examined the main characteristics of the document collection and focused on identifying emerging and trend topics and areas of focus.
The results of this study highlighted the potential that the integration of AI into AR, VR, and the metaverse can yield. Additionally, it revealed its wide applicability and capabilities of being effectively integrated into various domains. The study also confirmed the significance and novelty of the topic which showcases a significantly high growth rate (91.29%). Additionally, the study revealed the main research areas and directions and highlighted the following topics as the ones being more actively researched: “Education/Learning/Training”, “Healthcare and Medicine”, “Generative artificial intelligence/Large language models”, “Virtual worlds/Virtual avatars/Virtual assistants”, “Human-computer interaction”, “Machine learning/Deep learning/Neural networks”, “Communication networks”, “Industry”, “Manufacturing”, “E-commerce”, “Entertainment”, “Smart cities”, and “New technologies” (e.g., digital twins, blockchain, internet of things, etc.).
However, the study has some limitations. Specifically, the documents identified were retrieved from two databases and only English documents were examined. Since the goal of this study was to provide a general overview of the field, a more in-depth content analysis targeted to a specific domain was not carried out. As a result, there is a clear need for future studies to further analyze the integration of AI, VR, and AR across different settings through systematic literature reviews and case studies. Additionally, effective frameworks, standards, and guidelines on how to develop relative solutions and integrate them should be created. Emphasis should also be placed on examining and addressing the challenges and barriers associated with the effective integration of AI within XR environments, such as technical, hardware, and software limitations, algorithmic bias considerations, security and privacy issues, ethical concerns, as well as development and adoption hurdles. There is also a need to create valid evaluation metrics to assess its effectiveness. Future studies should also examine security, privacy, and ethical aspects associated with the use of AI, XR technologies, and the metaverse. Finally, it is important to explore users’ involvement, interactions, communications, perspectives, behaviors, and emotions while they are engaged within AI-enabled AR and VR environments as well as within the metaverse.