# A Subjective and Behavioral Assessment of Affordances in Virtual Architectural Walkthroughs
## 2 Background
### Affordances and Perceived Quality in Virtual Environments  
We do not objectively perceive environmental properties or objects; rather, we perceive what we can do [25]. The perception-in-action [26] process is facilitated by the opportunities presented to an organism by its environment, or the _situated affordances_ of the environment. The concept has been around for a long time, and a detailed explication is not within the mandate of this paper. However, it is important to emphasize that affordances are neither objective nor subjective; instead, they \"cut across the dichotomy of subjective-objective... Both physical and psychical, yet neither\" [27]. Affordances must therefore be understood in two ways: (a) affordances are properties of the environment; or (b) affordances are relations between an organism and its environment. Building on [PERSON]'s hedonic and pragmatic model [28; 29], we define four distinct affordance types that expand from more immediate operational goals to deeper biological or psychological needs. These are:  
1. Manipulation Affordances: The directly perceived affordances that speak to the physical/sensorial compatibility between the user and the object. 2. Effect Affordance: It describes the functioning of the object due to manipulation. It is also directly perceived based on cause-and-effect knowledge of the user. 3. Use Affordance: It relates to the physical and mental skills of the user utilizing the right cognitive or usage plans. 4. Experience Affordances: They are related to the psychological and biological needs of the user and are perceived only with correct knowledge and usage modes. Manipulation affordances are at the lowest level and are signified by motor goals performed in order to accomplish do-goals, i.e., the effect and use affordances. At the highest level are be-goals (or experience affordances) that motivate actions towards purposes [29]. Between them, they highlight the how, what and why of interaction possibilities. For example, a VE can afford manipulation to a user in the form of pressing a button (motor-goal). The effect affordance of the environment can associate the pressing of a button with the activation of an illumination object, e.g., a light on a wall--cause and effect. This combination and sequence of actions could be intended towards a use, such as illuminating the scene; the effect-and-use affordances use do-goals. The failure or fulfillment of a do-goal results in emotional consequences, such as satisfaction or annoyance. Returning to [PERSON] [30], the emotional (hedonic) aspects make up the experience affordance for a user--enabling the achievement of be-goals [31]. The pragmatic aspects of a user's experience come from the compatibility of the user's skills with the capabilities of manipulation--the effect and use affordances of the environment [32]. For a light to turn on when a button is pressed meets a users expectation of how life real-world action sequences work. A light illuminating a scene realizes the use for that action. When these actions are matched to the abilities of the user, their successful performance achieves be-goals inside VEs that can cause pleasure. On the contrary, failing to perform them can cause annoyance. The extent of the interactions available inside a VE and their resultant consequences afford experiences to users. [PERSON] et al. [33] examined how the availability of affordances in VR applications gives them an edge over physical reality in certain use-cases, e.g., simulation-based training. On the other hand, works [34] evaluating the perceptions of real-world affordances--such as texture, gradient, hand-size, hand-size, etc.--have found that they affect user's choices and emotional states within VEs. This paper builds upon the aforementioned works by focusing on the psychological aspects of affordances inside VEs. In particular, we focus on their influences on user perceived quality and the _sense of presence and plausibility_.