## 4 Proposed Methodology
### Study Design for Heuristic Evaluation
#### 4.2.1 Heuristic Customization  
Due to the radical changes in technology over the years, evaluating usability with the 10 heuristics (HEs) of [PERSON] and [PERSON] alone could not provide sufficient insights. In addition, because smart devices demand more context-specific heuristics rather than a generic set, the usability requirements of different user interfaces, audiences, and tasks require customized heuristics. In the process of tailoring the heuristics to the specific interface and task, the evaluation can be more efficient due to orienting the focus to the most relevant usability issues [58]. Based on the existing information in different studies, scant research on the customization of usability heuristics using these methods is available. Therefore, we combined two heuristic principles: one for the interface usability analysis and the other specifically designed for wearable devices. The HCI experts of our group designed 11 heuristics for the evaluation of smartwatches and applications. The researchers state that a more human-centered approach to wearable design must take into account human aspects, facilitating consideration of human factors during design phases [27]. These human factors would include users' needs, preferences, and expectations; moreover, human-centered wearable design contributes to a better user experience. As an innovative approach to design, human-centered design starts with understanding users' perspectives and designing accordingly [59]. Therefore, our selection of six heuristics (visibility of system status, match between system and real-world, consistency and standards, aesthetic and minimalist design, flexibility and efficiency of use, and error tolerance) were sourced from [PERSON]'s heuristics, while [PERSON] and [PERSON]'s heuristics (privacy, wearability, comfort, ease of use, and satisfaction) are also relevant and helpful in the design process of wearables and mobile applications. These are the heuristics that were unanimously agreed on in this \begin{table}
\begin{tabular}{c c} \hline \hline
**Scale** & **Description** \\ \hline
1 & Not a usability problem, no flaws, and issues in the application and watch \\
2 & Cosmetic usability problem, minor issues that can remain unnoticed \\
3 & Minor usability problem but low priority \\
4 & Major usability problem, usability improvements are required \\
5 & Usability catastrophe, must solve the issue \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Severity scale for heuristic evaluation. study and used in the subsequent evaluation process. They were further reviewed by three human-computer interaction (HCI) experts to ensure the consistency and validation of these heuristics. In order to provide a comprehensive assessment and evaluation of HEs, each item was broken down into multiple items. These 11 heuristics are defined below:  
* Self-descriptiveness: This heuristic is used to evaluate whether the design is user-friendly or not. Each screen header should define the purpose of that screen; additionally, the user should be able to know where they are when looking at the screen header and the sentences and words that have been used, i.e., when looking at the time, the header of that screen should be self-explanatory, or when the user touches on a button, there should be visual feedback that describes that action has been noted. For instance, if users delete something, successful deletion, or that object disappearing, provides the visual feedback. In total, we designed five items to obtain the mean severity value for this heuristic. * Consistency and standards: This heuristic identifies the need for user interface elements across different tasks or across different versions to be consistent in their language, icons, and symbolism. We designed four items specifically related to this heuristic. * Aesthetic and minimalist design: The [PERSON] and [PERSON] group [4] presented aesthetics and minimalism as their eighth usability heuristic.