## 2 Background  
### Immersive Technology  
Immersive technology describes the technologies that simulate visual, auditory, haptic, and motion realness [6] alone the Reality-Virtuality continuum [27], which has evolved into diverse taxonomies, such as mediated reality [28], the visuo-haptic reality-virtuality continuum [29], and the EPI cube (EPI stands for technological embodiment, psychological presence, and behavioral interactivity) [21], to describe constantly emerging multisensory technologies. In this continuum, VR is well-accepted as a completely synthesized virtual environment [6; 21], but the definitions of AR and MR are not settled. For example, [30] identified six MR definitions from the literature review and expert interviews: part of the Reality-Virtuality continuum, a synonym of AR, enhanced AR, a mixture of AR and VR, AR-VR remote collaboration, and physical-virtual environments alignment. Generally speaking, these definitions regard AR as either a subset, a component, or an equivalent of MR. Specifically, AR can display computer generated content (e.g., user interfaces and images) on real world scenes in real time [31], while MR can render virtual scenes, combine virtual scenes with real ones, or provide more complex interactivity, i.e., MR achieves a dynamic coexistence of virtual and real content in the same space. Furthermore, some researchers recently proposed extended reality (XR) to encompass AR, MR, and VR [32; 33]. Nevertheless, as XR is only an umbrella concept without distinct features, it is not analyzed in this paper.  
AR/MR/VR can achieve either high immersion by displaying the content on special devices such as head-mounted devices (HMDs) and cave automatic virtual environments (CAVEs) [34; 35], or low immersion with common displays of computers, smartphones, and so on. For user control, ordinary input devices such as keyboards, mice, and touch screens are sufficient for navigation and interaction in AR/MR/ VR applications [36], yet using special devices, such as a steering wheel and pedals for driving simulation, can enhance the immersive experience [6; 21].  
Moreover, virtual worlds (VWs) are the technologies that enhance the perceived immersion with character realness of the avatars and residents [37]. A VW is usually networked and situated with intelligent agents, allowing its users to freely interact with the virtual objects and intelligent agents, and communicate with each other [37; 38]. The definitions of these concepts are summarized in Table 1.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Concept** & **Definition** \\ \hline Augmented reality (AR) & Realtime display of computer-generated content over a real-world scene [31]. \\ \hline Virtual reality (VR) & Computer-simulated, interactive, and immersive virtual environments that isolate the user from the surrounding physical environment [39], using various immersion methods [6]. \\ \hline Mixed reality (MR) & The dynamic coexistence of virtual and real content in the same space [27]. \\ \hline Extended reality (XR) & An umbrella term for AR, VR, and MR [33]. \\ \hline Virtual world (VW) & Synthetic, persistent, immersive, and networked multi-users environments, allowing users represented as avatars to interact with other users and in-world content in (nearly) realtime [38]. \\ \hline \hline \end{tabular}
\end{table}
Table 1: Definition of AR, VR, MR, and VW.  
Notably, AR, VR, MR, and VW could induce different behaviors of consumers and have different influential mechanisms or effectiveness. Their differences are implicitly reflected in different virtual commerce application, leading to different purchase models. Nevertheless, the four types of immersive technology can be consolidated into the Reality-Virtuality continuum. Thus, an inclusive framework can be constructed to investigate the relation of purchase behaviors and application design from the four types of virtual commerce application, or even other types within the continuum.