# Evaluation of Methodologies and Measures on the Usability of Social Robots: A Systematic Review
## 4 Discussion
### Suggestion of Stimuli and Evaluation Technique by Assessment Conditions  
First, this study suggests appropriate evaluation stimuli according to the dimension of social robot assessment. Utilitarian robot and hedonic robot needed a different approach. When evaluating a utilitarian robot, participants should focus on its performance and function. Text, video and live interaction can show its function but the static image is insufficient to deliver the whole process of conducting the task. However, when the user evaluate hedonic robot, they will focus on its emotional value. A static image can describe robots appearance and facial expression better than text. Regarding concept of trust, it is difficult to illustrate the expected intellectual capacity of a robot in text or image. Therefore, video or live interaction would be recommended to assess trust between robot and user. Next, proper evaluation techniques according to the dimension of social robot assessment are proffered. Questionnaire and interview can cover all three dimensions of attitude towards a robot. In contrast, measuring biometric is only recommended for assessment in hedonic aspect. Biometric can be translated emotional arousal and valence into numbers, and it is applicable to evaluate a social robot in hedonic aspect. Last, video analysis is suitable for evaluation in utilitarian or hedonic aspects. Trust can be observed in a long-term relationship between robot and users, and it is insufficient to measure trust by biometric or video analysis. Measuring trust is needed deep dive into users and in-depth interview is the most appropriate way to evaluate trust in robot. To provide proper UX evaluation methodology and measures, ref. [65] was a good reference for this study. Ref. [65] propose new point of view to evaluate HRI, users' possibilities to recognize a robot's action and intention. They suggested UX evaluation process for HRI from preparation to identifying UX problem thoroughly. The overall procedure is described in detail for everyone and pointed out a meaningful issue that importance of defining context to set product goal and select appropriate UX evaluation type. They mentioned that the developmental stage of the product is one of the criteria to select UX evaluation type. It is important to find out the ecological problem of a product early in the development cycle, and even 'quick and dirty' evaluation is needed at that time. In this paper, we also indicate the importance of problem finding in the early stage of the development cycle and suggest an applicable type of evaluation stimuli and evaluation methodology for that. Additionally, they stressed the advantage of field study as an evaluation method. When evaluating a robot in a lab setting, sometimes we can observe that users are self-conscious and do unnatural behavior. So they said gathering more accurate data from multiple evaluation methodology will be complementary. We also agree with this point, and we put together the evaluation context of reference paper in table [11] and hope it could be helpful to select an evaluation method for practitioners. However, ANEMONE focused on the procedure of evaluation, not the evaluation measure level. They provided some examples of objective and subjective UX measure,but presented examples are not sufficient to design whole UX evaluation measure and its structure for practitioners. In this study, we try to provide as much measure as we can for practitioners to design UX evaluation easily. Also three categories we suggested as utilitarian aspect, hedonic aspect and trust could be a valuable foundation to create the base structure for the assessment of attitude toward a robot. Ref. [54] was also a good starting point of this study to understand the latest issues of interaction between human and social robots. Ref. [54] analyzed four trends and three challenges related to UX of HRI. These issues would be a useful basis for finding out the proper topic of future research.