# Subtitling 3D VR Content with Limited 6 DoF: Presentation Modes and Guiding Methods
## 4 Results: User Tests
### Results
#### 4.3.1. Test Condition: Presentation Modes  
The impact on presence of each of the considered subtitling presentation modes was assessed using the IPQ questionnaire [29], which is composed of 14 statements/items to be rated on a seven-point scale (1 to 7). In turn, the 14 items are categorized into four sub-scales:  
* _General Presence_: One item that assesses the general \"_sense of being there_\". * _Spatial Presence_: Five items that measure the sense of being physically and bodily present in the virtual environment. * _Involvement Scale_: Four items that measure the attention that the subject pays to the virtual environment and the involvement experienced. * _Experienced Realism_: Four items that measure the subjective experienced sense of realism attributed to the virtual environment  
Tables 3-6 provide a summary of the mean and standard deviation values of the answers of the participants for each of the scales, together with the statistical analysis to determine whether significant differences exist between the results obtained for each presentation mode, using a Wilcoxon Signed Rank test (with 95% confidence interval). Similarly, Figure 4 shows the boxplots of the obtained results for each presentation mode and IPQ scale, also indicating the situations in which significant differences were found. The results for all three tested conditions were positive, especially for the _Always-visible_ (Mode C) and _Comic-style_ (Mode B) presentation modes. The statistical analysis shows that, in the considered scenario and for the considered implementation, the use of _Always-visible_ subtitles provided higher presence than _Fixed-positioned_ subtitles (Mode A) for each of the IPQ scales. This is also the case for _Comic-style_ (Mode B) subtitles when compared to _Fixed-positioned_ subtitles (Mode A) in terms of the General Presence and Involvement scales. _Always-visible_ subtitles (Mode C) also provided higher presence than _Comic-style_ subtitles (Mode B) with regard to the Experienced Realism scale. This may be due to the fact that the bubbles in which the subtitles were presented resemble comics and animation content, thus having an impact on the experienced realism. With regard to the results from SSQ, no significant effects/symptoms were found to be caused by the VR experience, in any of the test conditions. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \begin{tabular}{c} **Presentation** \\ **Mode** \\ \end{tabular} & \begin{tabular}{c} **Mean** \\ **Deviation** \\ \end{tabular} & \begin{tabular}{c} **Standard** \\ **Always-Visible** \\ \end{tabular} & \
\begin{tabular}{c} **Compared to** \\ **Fixed-Positioned** \\ \end{tabular} &
\begin{tabular}{c} **Compared to** \\ **Comic-Style** \\ \end{tabular} \\ \hline Always-visible & 5.05 & 1.873 & - & _p-value = 0.04_ & _p-_value = 0.4054 \\ Fixed-positioned & 4.91 & 1.785 & _p-value = 0.04_ & - & _p-_value = 0.0609 \\ Comic-style & 5.025 & 1.907 & _p-_value = 0.4054 & _p-_value = 0.0609 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: IPQ—Spatial Presence Scale. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \begin{tabular}{c} **Presentation** \\ **Mode** \\ \end{tabular} & \begin{tabular}{c} **Mean** \\ **Deviation** \\ \end{tabular} & \begin{tabular}{c} **Standard** \\ **Always-Visible** \\ \end{tabular} & \
\begin{tabular}{c} **Compared to** \\ **Fixed-Positioned** \\ \end{tabular} &
\begin{tabular}{c} **Compared to** \\ **Comic-Style** \\ \end{tabular} \\ \hline Always-visible & 6.291 & 0.806 & **-** & _p-value = 0.0032_ & _p-_value = 0.0726 \\ Fixed-positioned & 5.583 & 0.928 & _p-value = 0.0032_ & - & _p-value = 0.0125_ \\ Comic-style & 5.958 & 0.859 & _p-_value = 0.0726 & _p-_value = 0.0125 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 3: IPQ—General Presence Scale.