## 5 Discussion and Conclusions
### Limitations and Future Work  
Characteristics of a participant such as age, gender, education level, and so on may play an important role in the participants' responses, but we did not analyze the relationships between these characteristics and participants' responses because such analysis is beyond the scope of this paper. The purpose of this paper is to explore the differences in participants' behavior in philosophical dialogues with humans and robots. Investigating what role the characteristics of a participant play in philosophical dialogue with a robot is the next task based on the findings of this study. The topic of philosophical dialogue in this experiment was limited to BLM, which was not so familiar news to typical Japanese. The results may be different if the experiment was conducted in other countries such as the US. In addition to the above point, our participants were only Japanese. According to [PERSON] and [PERSON] [27], Americans perceived more comfortableness with a robot with a higher quality of human essences than Japanese. Based on their finding, since philosophy is an effort to explore human nature, Americans may prefer to engage in philosophical dialogue with a robot than Japanese. As a result, Americans may respond to the robot interlocutor at the same length as the human interlocutor. We believe that the above points are exciting for future work. The appearance of the robot was limited in this experiment. It remains the possibility that other realistic androids or more deformed pet robots will have different interactions. Furthermore, if robots become an everyday object and people get used to them just like they do with smartphones today, the results may be able to change. In this study, we believe that the anthropomorphism of the robot plays a role in facilitating the way humans respond to the robot's questions. According to a survey paper on anthropomorphism in human-robotinteraction [28], many studies have pointed out that robot anthropomorphism facilitates human interaction. Even in philosophical dialogues, the anthropomorphic nature of the robot is likely to give humans the sense that they are interacting with intelligent individuals. Relating to the appearance, the robot's size may have affected the impression of cuteness and brought about a sense of familiarity. In the experiment, some participants who talked with the robot commented less hesitation toward the robot because of its cute appearance. Since some studies [29; 30] have shown that the height and eye level can be intimidating to participants, we consider that the robot's facial appearance and size contributed to such a feeling. However, to discuss the effects of anthropomorphism and size in detail, we need to conduct experiments similar to the present study using robots with different degrees of anthropomorphism and sizes. This paper did not analyze the complexity of the participants' responses to the robot's questions, even though it is one of the essential features in philosophical dialogue. This is because defining the complexity of the responses was difficult. For example, it is hard to quantify how complex or simple concept words like \"freedom\" and \"race\" are. Additionally, the sentence \"It is important to solve problems through discussion with others\" and the sentence \"Democracy is important\" mean similar concepts, although the lengths of the sentences are different. It is not easy to quantitatively determine which of these is more complex. However, it is meaningful to mention the difference in the complexity of participants' responses between the human and robot interlocutor groups, even if that mention is based on subjective and quantitative observations. From our subjective point of view, the difficulty of the words and concepts used by the participants appeared to be comparable between the human and robot interlocutor groups. Most participants in both groups did not use advanced terms that are learned in higher education, nor overly simple words that could be said to children.