# Collaborative Facilitation and Collaborative Inhibition in Virtual Environments
## 2 Method
### Procedures and Experimental Design  
As shown in Figure 1, participants were randomly assigned to one of three experimental conditions, namely individual (DRM Single), nominal (DRM Nominal) and collaborative (DRM collaborative). The sample size enabled the experimental conditions to be balanced in terms of both gender of the participants and number of members in the groups (pair, triplet, quartet). Also, the members of every group were unknown to each other. Before starting the experiment, respondents \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Dimension** & \multicolumn{2}{c}{**Test Condition**} & **Collaborative Condition** & **Power** & **Type I Error** & **Required** \\  & & **Mean (SD)** & **Mean (SD)** & **1 - \(\beta\)** & **\(\alpha\)** & **Sample Size** \\ \hline \multirow{2}{*}{Studied Words} & Nominal & 7.6(1.8) & 8.3(1.5) & 0.8 & 0.05 & 72 \\  & Individual & 7.5(1.8) & 8.3(1.5) & 0.8 & 0.05 & 56 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sample size estimation to compare two means from two samples with two sided equality hypotheses, with an actual sample size \(n_{b}=72\), with \(K=\frac{n_{a}}{n_{b}}=1\). were asked to fill out an anonymous questionnaire to collect socio-demographic and psychological data (Demographic and Psychological Assessment--DPA). In the individual condition (DRM Single), the participants performed the DRM test (T) alone and with the sole presence of the researcher. In this condition, all phases of the experiment took place in a small room of the Social Psychology Laboratory of the University of Florence. This room was equipped with a single laptop protected by the rigid structure. After the DPA, one participant was accompanied by a researcher to the small room while the other participants were waiting in a larger room of the laboratory along with a second researcher. During the DRM Single, the participant in the small room was told to remember a randomly assigned list of words (List A or List B--the two lists were balanced within each experiment). The list was presented by a video player for thirty seconds. During the mathematical distractor (D), the respondent was asked to complete a 3-min mathematical filler task to hinder rehearsal in short-term memory [58]. We used two mathematical fillers that were balanced across the experiment. Finally, during the DRM test (T), the subject was asked to recall the words of the displayed list by selecting words from a new list consisting of studied and non-studied words and as well as a critical lure [11]. Unlike the individual condition, the nominal and the collaborative condition took place in a large room of the laboratory. This room was prepared to provide from two to four laptops (according to the size of each participant group). Each laptop was protected by rigid structures that obstructed the view of the respective screens. Before the DRM Nominal and the DRM Collaborative, all participants were invited to interact with each other anonymously for 3 min within a VE (i.e., a chat line; grouping phase G). In order to focus on the VE, headphones playing white noise were used in order to avoid lacks of attention due to sounds coming from the real environment. As in the individual condition, both the nominal and the collaborative condition required that participants remember a randomly assigned list of words presented by a video player for thirty seconds and, then, they completed a mathematical distractor (D). Figure 1: Experimental design. Note. In figure, the entire procedure for each protocol (i.e., Protocol IA-IB; Protocol IIA-IIB; Protocol IIIA-IIIB; Protocol IVA-IVB) is reported. Groups (i.e., subsamples) were balanced for all conditions (i.e., word list, order of experimental conditions, group size and gender composition). The DRM test (T) mode was what differentiated the nominal from the collaborative condition. In fact, in the nominal condition, each participant performed the DRM test (T) alone, in the largest room of the laboratory, with the presence of all the other members of the group.