# Can Gestural Filler Reduce User-Perceived Latency in Conversation with Digital Humans?
## 5 Study 2
### Discussion  
Our results show that CF, GF, and GCF can mitigate user-perceived latency more than NF (supporting H1). In the previous study, there were attempts to reduce the perception of latency using conversational fillers of digital humans [39, 41]. We found that the gestural  
Figure 8: Results of the subjective measures: (**a**) user-perceived latency, (**b**) behavioral naturalness, (**c**) willingness, (**d**) impression, (**e**) discomfort, and (**f**) competence. (*: \(p<0.05\), **: \(p<0.01\), **: \(p<0.001\)). \begin{table}
\begin{tabular}{c c c} \hline \hline  & \(\chi^{2}\) & \(p\)**-Value** \\ \hline User-perceived latency & 59.477 & \(<\)0.001 \\ \hline Behavioral naturalness & 66.031 & \(<\)0.001 \\ \hline Willingness & 50.109 & \(<\)0.001 \\ \hline Impression & 42.301 & \(<\)0.001 \\ \hline Discomfort & 22.510 & \(<\)0.001 \\ \hline Competence & 40.208 & \(<\)0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary of the Friedman test results. Figure 9: Results of the gaze time during the delayed responses. (*: \(p<0.05\), **: \(p<0.01\), ***: \(p<0.001\)). filler can also effectively mitigate user-perceived latency (Figure 8a, Table 3). Even though the latency was eight seconds in all conditions, the participants felt the length of latency differently. For the NF condition, participant P17 commented _\"The response time was so slow that I didn't feel like a real conversation.\"_. Regarding GF condition, participant P22 mentioned _\"I think the answer time was faster than other digital humans.\"_. In the delay situations, the digital human acting dormant, could lead to breaks in social presence of the participants, therefore increasing their perceived latency. According to behavioral naturalness, our results statistically support H2 (Figure 8b, Table 3). For CF condition, P13 said, _\"When the digital human says, \"Please wait a minute.\" I was a little distant. It would be more natural with a gesture or facial expression\"_. Similar to P13, some participants for NF commented that they felt awkward and that it would be better for digital humans to take some action than just staring ahead. Furthermore, some participants for the CF and GCF conditions commented that it would be more natural if the digital human says things like _\"Hmm.\"_ instead of _\"Please wait a minute\"_ or _\"I am looking for information\"_. These comments differ from previous studies' results that the lexical conversational filler is better than the non-lexical conversation filler [41]. It seems that more research related to the conversation filler of digital humans is needed. For willingness, the GF and GCF conditions received statistically higher scores than NF and CF (Figure 8c, Table 3). The participants evaluated that they would like to talk more with digital humans using the gestural filler in the future. Participant P29 for GCF commented _\"I felt like I was having a real conversation. I want to talk to her more\"_. It seems that gesture fillers can improve the usability of digital humans. Regarding impression, the GF and GCF conditions received significantly higher evaluation than NF and CF (Figure 8d, Table 3). The participants had a good impression of the digital humans with gestural fillers. Participant P20 for the NF condition said _\"Unlike other digital humans, it was a little scary to say nothing and blink when the delay occurred\"_. However, P20 and P31 for the GCF condition commented _\"I felt like he was likable and friendly.\"_ and _\"I felt like I was talking about a vacation plan with my real friend.\"_, respectively. This is in line with the previous study that non-verbal cues play an important role in building rapport and bonding during the conversation [43; 44]. Furthermore, it is one of the main advantages of embodied conversational agents that they can utilize their bodies like actual humans. Our results partially support H4. The participants felt more discomfort with digital humans in the NF than the GF and GCF conditions (Figure 8e, Table 3).