## 5 Discussion  
Several studies that examined the cognitive dimension of learning applications in social VR differentiate descriptive or declarative [92] from procedural knowledge [85], while others examine retention [91], skill acquisition [77], and comprehension [67]. Reported success for any of these outcomes and measures, however, does not equate to or automatically result in deep and meaningful learning (DML). Virtual worlds have been found to be suitable for knowledge-based, abilities-based, or skill-based learning outcome achievement [37]. Figure 5: Blended Model for Deep and Meaningful E-learning in Social Virtual Reality Environments. Nevertheless, DML has not been widely researched in the context of distance education with the use of SVREs. In this context, our research yielded just one study with an explicit focus on DML [86]. There are several factors that could explain this phenomenon. First, the topic of DML in itself is quite complex and not fully developed. Evaluating deep learning with validity and reliability in any educational settings and social conditions can be very challenging. For instance, one common instrument to estimate deep learning is a questionnaire. Self-reporting certainly has its limitations [13]. Furthermore, actual student behavior and performance could differ from their self-perceptions [10]. The assessment of meaningful learning should aim at higher-order processes and can, therefore, be daunting. Three-dimensional virtual learning environments (SVREs) can serve multiple purposes within an e-learning program [99]. In one study, trainees participating in desktop virtual reality experiences achieved superior outcomes in declarative knowledge, procedural knowledge, and knowledge retention than the control groups did [29]. The element of immersion in a situation, a problem, or a professional competence allows educators to re-orient the depth of learning outcomes for online educational experiences from learning about a subject to learning by doing and by emulating a role, and this enables deep conceptual and procedural knowledge to be built of a discipline, which is far superior to a superficial declarative knowledge about the content area [100]. Elaborating on the importance of teacher perceptions and learning theory in relation to technical aspects of the learning environment, as [PERSON] and [PERSON] [30] point out (p. 774), \"carefully designed learning activities are more important than an exotic interface that contributes to intuitive interaction.\" One general classification of learning activities in SVREs lists the relevant activities as follows: content creation, content exploration and interaction with the content, social interaction, gaming, and participation in representations of real-life events and situations [40]. Indeed, a meta-analysis of desktop-based virtual reality instruction found no difference between high and low research design quality, which is an indicator of the robustness of its benefits for learning [37]. Moreover, a high degree of sensed presence in SVREs correlates with learning performance [30]. More importantly, this affordance of the medium and the induced sense of presence were not influenced by the design of the educational environment [40]. Learning activities in SVREs can be combined with traditional instructional strategies in a meaningful way; that is, learning achievement increased when simulations were utilized as supplementary practice than when they were planned as autonomous experiences [37]. SVREs can be used as platforms to provide authentic, realistic, cognitively challenging experiences in engaging, motivating environments for open-ended social, collaborative interactions and for intentional, purposeful, self-directed learning. In other words, they can embrace all three DML dimensions: mind, emotions, and a community for mastery, autonomy, and connectedness [101]. Learning in a 3D virtual environment can elicit a spectrum of possible emotional states, both positive and negative [88].