## 1 Introduction
### Low-Fidelity Prototypes for In Situ Testing  
Studying prototyping methods comparatively [11] requires a clear definition of each method that is used. The definition of low-fidelity prototyping used in this study was formulated by [PERSON] [11]: \"...Low-fidelity prototyping, as we understand it, is the visualization of design ideas at early stages of the design process. The result is a prototype which is simple and whose development does not need very much time. It may be developed using paper and other \"low-fidelity-materials\" or using any user-friendly programming tool...\". In contrast, high-fidelity prototyping can be defined as: \"...computer-based, and usually allow realistic (mouse-keyboard) user interactions. High-fidelity prototypes take you as close as possible to a true representation of the user interface. High-fidelity prototypes are assumed to be much more effective in collecting true human performance data (e.g., time to complete a task), and in demonstrating actual products to clients, management, and others [12]\". [PERSON] emphasizes that high-fidelity prototypes offer more interaction [13]. Traditional low-fidelity prototyping, such as paper models, is currently used in design education and shows limitations in terms of realism and user interaction. When feedback is necessary early in the process, [PERSON] states that it is always a good idea to test early materialisations of a product with the target user group [14]. Furthermore, low-fidelity prototypes are best tested in the field to account for the external validity of its concept. There are many benefits to in situ testing such as revealing implicit usability problems, extended periods of test sessions, realistic tasks, and homeless to the environment [15]. However, testing in the field has several drawbacks. In the first place, organising transportation can be a tedious task, especially when transporting large prototypes or when travelling to remote locations. A recent study by [PERSON] evaluates the role of paper prototyping in combination with augmented reality (AR); she specifically points to the difficulties of requirement elicitation in low-fidelity prototypes [16].  
A goal of this research is to evaluate how valuable the environment is in testing in situ in the early stage of the development process. There is ample research on comparing in situ testing with in vitro testing. [PERSON] [17] argues that testing in the field may be time consuming but can hold insights on how the user behaves in the context of use. A recent study by [PERSON] [18] points to the benefits of early low-fidelity testing. However, in the case of physical prototyping, testing in situ remains expensive, e.g., [PERSON] [19] built proactive systems and devices, installed these systems into homes, and interviewed and observed the people who used them [17]. This approach lends itself to utilising the elements of participatory research. In the new field of participatory research, reflection and action are carried out in a sequential manner to collect local knowledge. This forms the basis for research and planning. Moreover, these steps are carried out with and by local people rather than on them [20]. In another study, [PERSON] [21] argues that although low fidelity plays a central role to design, little attention is geared at understanding low-fidelity prototyping itself. For lo-fi prototypes to be successful, they should evoke scenarios of the future, tell stories and communicate a vision for the future. High-fidelity prototypes for validation testing offer the most realistic experiences. Their role is simulating experiences that are as close to reality as possible, after general ideas have been challenged and fundamental choices have been made.