# Social Responses to Virtual Humans: The Effect of Human-Like Characteristics
## 2 Experiment #1: Social Facilitation
### Design and Procedure  
The present study was a 6 (virtual human type: facial appearance only, voice recordings only, voice synced facial appearance, facial appearance conveying emotion, voice recordings conveying emotion, voice synced facial appearance conveying emotion) \(\times\) 3 (task type: anagram task, maze task, modular arithmetic task) \(\times\) 2 (task complexity: easy, hard) \(\times\) 4 (presence: alone, presence of a human, presence of a virtual human, and presence of a graphical shape) mixed design. We extended the previous study on the social facilitation effects of virtual humans [36] by adding the virtual human variable with six types of manipulation. All participants did both easy and hard versions of all task types in all presence conditions. Only the virtual human type was a between-subject factor, which varied the virtual human's characteristics. Each participant experienced one of the virtual human types in Table 1. Conditions without conveying emotion conveyed neutral facial expression or neutral voice. Note that, although an underlying model for an emotional expression is necessary for an effective emotional expression, because we are investigating the mere presence effect of emotion, we decided to limit our conditions to conveying an emotion (happy) or non-conveying an emotion (neutral). Voice recordings only condition did not have a facial appearance but only voice implementation. The presence of a graphical shape depicts a minimal visual interaction with the participant to make sure that any effect of a virtual human was due to its human-like characteristics and not due to the mere presence of a graphical component. The two within subjects factors (task complexity, presence) were crossed to produce eight types of trials, in which participants did:  
* a simple task alone
* a simple task in the presence of a virtual human
* a simple task in the presence of a graphical shape
* a complex task alone \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**The Type of Virtual Human** & **Facial** & **Voice** & **Emotion** & **Cover Story** \\ \hline A: Facial appearance only & Yes & No & Neutral & By text \\ \hline B: Voice recordings only & No & Yes & Neutral & By voice \\ \hline C: Voice synced facial appearance & Yes & Yes & Neutral & By voice \\ \hline D: Facial conveying emotion & Yes & No & Happy & By text \\ \hline E: Voice conveying emotion & No & Yes & Happy & By voice \\ \hline F: Voice synced facial conveying emotion & Yes & Yes & Happy & By voice \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The types of virtual humans manipulated in the social facilitation experiment. Figure 3: The layout of the experiment. a complex task in the presence of a virtual human  
a complex task in the presence of a graphical shape  
Every participant experienced multiple instances of each of the eight trial types. The order of the presence factor was varied across participants using a Latin square. That is, some participants did the first set of tasks in the presence of a human (H), the next set in the presence of the graphical shape (G), the third set in the presence of the virtual human (V), and the fourth set alone (A). The four possible orders were:  
\(\bullet\) \(\mathrm{H}\to\mathrm{G}\to\mathrm{V}\to\mathrm{A}\)  
\(\bullet\) \(\mathrm{G}\to\mathrm{V}\to\mathrm{A}\to\mathrm{H}\)  
\(\bullet\) \(\mathrm{V}\to\mathrm{A}\to\mathrm{H}\to\mathrm{G}\)  
\(\bullet\) \(\mathrm{A}\to\mathrm{H}\to\mathrm{G}\to\mathrm{V}\)  
Within a particular presence situation (e.g., virtual human), participants did a block of anagrams, a block of mazes, and a block of modular arithmetic problems.