## 7 Limitations and Future Research  
There are several limitations in this study that are worth noting. First, this experiment was conducted online in order to reach as many participants as possible, and to overcome additional external obstacles. However, the fact that it was an online experiment could have hindered the participants' concentration levels and impacted the results, even though careful measures (e.g., manipulation checks and quizzes) were included. It is hoped that the strict screening of the data that failed either of the two manipulation checks supplemented the findings.  
Second, this experiment required a computer, which is not the most popular medium for voice shopping. In addition, the fact that a computer was used to set up the smart speaker for the experiment could have created bias among the participants. Thus, visiting a link seemed less likely to affect the participants, compared to other options. Moreover, due to some technical difficulties, the sequence of the items that the participants were asked to purchase was fixed (i.e., (1) computer; (2) milk; and (3) tour), which could have impacted the results.  
Finally, this study revealed how providing voice reviews in voice shopping can increase trust in voice shopping but did not measure whether the newly suggested VUI increases user satisfaction and reduces frustration with the voice shopping experience. We thought measuring user satisfaction is apt to subjective feelings, so we measure the user experience through whether trust in shopping was improved instead of checking user satisfaction. However, not measuring user satisfaction for voice interfaces may be a limitation of this study, given that measuring user satisfaction for new VUI can help improve VUI development.  
Although this study mimicked the latest voice shopping experience, other methods and VUI characteristics should be considered when designing a voice shopping platform. Because VPIs are not suitable for providing users with abundant information, the current flow might not be the best strategy for voice shopping. For the future study, finding new ways to promote voice shopping that best fits its medium could be beneficial. For example, voice shopping could make recommendations to users, instead of simply assisting them in a search for certain items. More specifically, if data from SNSs is used, then the voice shopping platform could remind users that an anniversary or birthday is approaching, after which it makes recommendations about presents that are currently popular, gifts purchased the most on certain holidays, and sales promotions for items previously viewed by the users. In this regard, finding new ways to influence people to purchase items through voice shopping could be beneficial, both theoretically and practically, since it can contribute to the study of human-voice assistant interactions and develop the voice shopping market.  
**Author Contributions:** Conceptualization & Validation, J.S., D.L. and I.P.; Writing--original draft, J.S.; Writing--review & editing, J.S. and I.P. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by the MSIT (Ministry of Science and ICT), Korea, under the ITRC (Information Technology Research Center) support program (IITP-2021-0-02051) supervised by the IITP (Institute for Information & Communications Technology Planning & Evaluation).  
**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.  
**Conflicts of Interest:** The authors declare no conflict of interest.