# Enhancing Human-Agent Interaction via Artificial Agents That Speculate About the Future
## 5 Discussion
### Limitations  
There are a number of limitations to this research, both theoretical and technical, of which we note a few specific ones here. First, one major limitation is the use of the English language for comparison. Many studies in psycho-linguistics and cognitive science focus on comparisons of English versus some second language, but obviously, the linguistic world is much broader than that, and there may be idiosyncrasies about the English language that are not representative of all languages [94]. Moreover, given the global popularity of American pop culture, often even monolingual speakers of another language have likely been exposed to at least a small amount of English during their lifetime, which is problematic. Obviously, there are logistical constraints on the number of languages for which we have access to native L1 speakers in any one geographical location, which was part of the reason the study here was limited to two languages (Korean and English). Thus, if we want to expand the number of languages we compare in HRI/HAI research, it will be necessary to find new ways of doing research, perhaps by using international collaborative networks of researchers in different locations. We discuss this issue at length in another paper [22]. Second, there are potentially significant differences between virtual agents and physical agents when it comes to human interaction, though to what degree is still subject to debate (see Section 5.2). This topic has been extensively studied in the field of HRI, including some of our own past work [95; 96]. Nevertheless, the experiments described here should be replicated in the future on a variety of HRI/HAI platforms, both physical and digital, to compare the consistency of the results. However, there are some technical challenges in transferring knowledge gained from virtual experiments onto physical robot platforms, which has been discussed elsewhere [97]. Even simple things like physical lip-syncing during speech by a robotic face can represent significant engineering challenges. Third, we note that although the sample sizes used here were judged sufficient as they were based on the rather large effect sizes (>0.8) observed in our previous studies on bilingual human-agent conversation [49; 57; 58; 61], there is a need to replicate these findings on bigger sample sizes for further verification. This exploratory study can hopefully serve as the groundwork for that from a methodological standpoint. Likewise, some of our suggestions from Section 5.2.1, such as the comparison of slang use and standard use of language, could be investigated during those larger experiments to explore the _socially situated context_ of how language is used during human verbal behavior in order to disentangle the interaction of language (i.e., lexicon) and culture. Finally, there needs to be more exploration into how the appearance of an avatar/robot might affect speech interactions. There has been some work on this aspect by other researchers, though not in the exact same context as the experiments here [98; 99]. We did not consider that in this research study because the appearance of the virtual avatar was purposely fixed so that we could evaluate other factors, though we are currently running another set of experiments that do vary the physical appearance. Suffice it to say, additional research is needed. Conceptualization, C.C.B., S.Y.K. and B.W. ; Methodology, C.C.B., S.Y.K. and B.W. ; Software, Y.-H.B. and J.-H.Y. ; Formal analysis, C.C.B., [PERSON] and [PERSON]; Investigation, C.C.B., [PERSON] and [PERSON]; Writing--original draft, C.C.B. ; Writing--review & editing, [PERSON] and [PERSON]; Funding acquisition, C.C.B. All authors have read and agreed to the published version of the manuscript. This work was supported by a grant from the National Research Foundation of Korea (NRF), under grant number 2021R1G1A1003801. Data Availability Statement: Data used in this study may be available in a de-identified form upon request from the authors.