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Interactivity refers to how and to what degree people interact with a virtual system (Bucy & Tao, 2007). While interactivity has been studied from various perspectives in relation to technology (e.g. websites) the focus on 3D environments has been limited (Yun, 2007). Interaction has often been seen as the concept relating to active participation in a virtual environment (Bucy & Tao, 2007). Sundar (2004) clarified that interaction was a function of the user. With a focus on the user as the determinant of interaction, manipulating interaction in an experimental setting became difficult. Therefore, interaction needed to be considered a function of media technology as suggested by Sundar (2004). This led to a distinction in terminology: interactivity and interaction. Interactivity here is viewed as an affordance of the technology while interaction is treated as resident in the user.

Like many concepts in virtual environment research, interactivity was adopted from the communication field where the meaning pertained to interactions between people (i.e. human-to-human interaction) or people and content (i.e. human-to-content interaction). Communication-based interactivity was essentially the sequential messaging in response to previous messages (Rafaeli, 1988 in Yun, 2007). The key to interactivity for technology lies in response time (Steuer, 1992; Yun, 2007), and is due to the form of involvement of the user

Psychological Immersion Involvement Attention Affect User-Based

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– active or passive. Andersen (1997) in Yun (2007) indicated this had to do with the level of control over the interaction that was necessary to become a part of the content.

2.3.1 Navigation as a type of interaction

Interactivity has been widely accepted as a form of communication with a synthetic environment (Bucy & Tao, 2007). In virtual environment research, interactivity is heavily focused on the technological aspects of the virtual environment system. Bowman and Hodges (1999) classified interaction in terms of technology. Steuer (1992) generated a list of three categories based on their research where interactivity consisted of: a focus on speed – the rate input could be assimilated (i.e. Response time), a focus on range - the number of possible actions at a given time, and a focus on mapping - the ability of a system to map its controls to changes in a natural/predictable manner.

Bowman, Kruijff, LaViola Jr., and Poupyrev (2005) later defined interactivity in terms of technology, specifically input devices for particular types of interaction. Bowman et al. (2005) divided interaction into two main components: manipulation/selection and

navigation. The operationalization of manipulation/selection encompassed three basic actions: selection, manipulation, and release. These three actions could be performed with objects within a 3D virtual environment. Within navigation, Bowman et al. (2005) added that travel and wayfinding were essential parts of navigation. This led to the issue of

differentiating interactivity from navigation. Sundar (2004) furthered this idea of interactivity as different from navigation but, only so far that navigation was considered a type of

interactivity. In considering navigation as part of interactivity, the operationalizations of travel and wayfinding also became a sub-component of interactivity.

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Navigation presented similar complications in its definition as interactivity in that it was commonly associated with the user rather than the technology (Balakrishnan & Sundar, 2011). Balakrishnan and Sundar (2011) re-conceptualized it as navigability, i.e. the

affordance for navigation thus recasting it from a user-centric to technology-centric

perspective. In their study, navigability was further broken down into two main technology- based aspects: traversability and guidance, which enabled travel and wayfinding respectively. Balakrishnan and Sundar (2011) explained that “traversability is defined as the affordance to move large distances in a virtual environment as a function of (1) environmental constraints and (2) steering control” (p. 164). It was found that steering control had significant influence on spatial presence. Similarly, this study looked at the technology aspects of navigation to represent interactivity with a specific focus on traversability.

2.3.2 Interactivity & immersion as defining characteristics of VR

Several studies have suggested that both immersion and interactivity were crucial to spatial performance measures and user experience (Bowman & McMahan, 2007; Steuer, 1992; Zeltzer, 1992). Although no direct connection between immersion and interaction had been identified, Zeltzer (1992) generated a taxonomy for exploring virtual reality systems consisting of three characteristics: autonomy, interaction, and presence. As with many studies, the term ‘presence’ was used by Zeltzer (1992) in an encompassing manner. As Schuemie, Van Der Straaten, Krijn, & Van Der Mast (2001) stated, Zeltzer’s ‘presence’ was more closely related to immersion as defined by Slater and Wilbur (1997). Therein, the taxonomy for exploring virtual reality systems could be recharacterized as: autonomy, interaction, and immersion. This showed the importance of considering immersion and interactivity as viable virtual environment attributes which, could be implemented to

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influence the relationship with spatial performance measures and user experience. Following the same idea of exploring virtual reality systems, the same taxonomy could be considered as immersiveness and interactivity. With this model for exploring virtual reality systems, the impact on user experience measures, spatial presence in particular, could be examined.

Another more direct connection for looking at 3D virtual enviornment attributes from the concepts of immersion and interaction came from the “human-VE interaction loop” model developed by Bowman and McMahan (2007). In this loop, a model was sent to the computer where rendering software delivered it to display devices for a user to view. The user then utilized an input device sending a message back to the computer system to update the rendering software. In considering this model, immersion and interaction were central to user participation. Despite the inclusion of some form of interaction in their model, the concept of interactivity was intentionally left out of the Bowman and McMahan (2007) analysis. While their findings provided great insight into the relationship between virtual environments attributes of immersion on spatial performance measures, it did not consider interactivity as having any direct contribution to the overall outcome.