## 5 Concluding Remarks  
The small number of participants in the present study who were from a single demographic background (i.e., 30 younger Japanese adults) limit the generalizability of its findings. Future research can address these limitations by including larger sample of gender-diverse individuals from various cultural backgrounds and age range (i.e., children, adolescents, and older individuals in addition to younger adults only). Such diversified studies will allow for more informed conclusions via broader examination of the potential effect of age, culture, and gender on present findings.  
Another venue in which the future research can further the present findings is through adaptation of different types of robots for touch interaction to verify how such variety may affect the perception of physical interaction by human subjects. For instance, these studies may consider the change in degree of trust, likeability, etc. by human subjects as a function of varying level of human-likeness of such physically interacting agents. In the same vein, they may also compare the human-likeness versus more animal-like look-and-feel to verify how such a change in appearance could help in addressing human subjects' affective stance toward robots.  
Another possibility to extend the present findings is through introduction of various robot's behavioural paradigms. Specifically, the present study used the same robot's touch-behaviour that followed fixed references for the robot-arm trajectories and people's postures. In this regard, it becomes more interesting to verify whether the robot ability to adjust its touch as per individuals' pose and posture can affect their attitude toward robot.  
Conceptualization, methodology, formal analysis, data curation, writing--original draft preparation, writing-review and editing, and funding acquisition: S.K. The author has read and agreed to the published version of the manuscript.  
This work was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Number JP19K20746.  
This study was carried out in accordance with the recommendations of the ethical committee of the Advanced Telecommunications Research Institute International (ATR) (approval code: 19-501-4).  
**Informed Consent Statement:** All subjects signed a written informed consent form in accordance with ethical approval of the ATR Ethics Committee.  
**Acknowledgments:** The author would like to thank Advanced Telecommunications Research Institute International (ATR) for providing the robot-arm and the experiment's room, [PERSON] for translating the content of the questionnaire to Japanese, and [PERSON], whose assistance allowed the experiment progress smoothly.  
**Conflicts of Interest:** The author declares no conflict of interest. The funder had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.  
Appendix A Effect of the Participants' Personality Traits on Their Responses to Questionnaire's Items Q1 through Q5  
We observed non-significant effects of participants' personality traits and their interactions with their gender on their responses to Q1 (Table A1), Q2 (Table A2), Q3 (Table A3), Q4 (Table A4), and Q5 (Table A5).