## 4 Results and Discussions
### Eye Tracking and Keystroke Logging Data Analysis
Figure 3 illustrates overall pupil dilation per participant, while Figure 4 presents gaze event duration across participants, capturing fixation behavior during translation tasks. In Figure 3, some participants, such as P01 and P09, exhibit consistently higher median pupil dilation, whereas others, such as P18, show lower median pupil dilation. These variations may reflect differences in cognitive load, translation expertise, or individual processing strategies. The presence of numerous outliers in both translation directions suggests that certain translation segments required significantly greater cognitive effort, potentially due to challenging lexical choices, ambiguous structures, or increased decision-making demands. Similarly, Figure 4 highlights variation in gaze event duration across participants, providing insights into fixation behavior during translation. Some participants, such as P10 and P20, display longer gaze event durations, \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multicolumn{6}{l}{**English-to-Chinese (E-C) Translation Direction**} \\ \hline Variable & Min & 1 st Qu. & Median & Mean & 3 rd Qu. & Max \\ \hline PupilLeft & 1.690 & 2.658 & 2.885 & 2.853 & 3.012 & 3.912 \\ \hline PupilRight & 1.466 & 2.645 & 2.811 & 2.852 & 3.043 & 4.197 \\ \hline AVGpupiltillation & 1.812 & 2.655 & 2.853 & 2.853 & 3.029 & 4.033 \\ \hline \multicolumn{6}{l}{**Chinese to English (C-E) Translation Direction**} \\ \hline Variable & Min & 1 st Qu. & Median & Mean & 3 rd Qu. & Max \\ \hline PupilLeft & 1.800 & 2.606 & 2.827 & 2.817 & 3.004 & 4.000 \\ \hline PupilRight & 1.899 & 2.594 & 2.773 & 2.838 & 3.072 & 4.184 \\ \hline AVGpupildillation & 1.927 & 2.602 & 2.799 & 2.828 & 3.032 & 4.090 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary of statistics for average pupil dilation. indicating that they spend more time fixating on specific areas before making translation decisions. Conversely, others exhibit shorter fixation durations, suggesting a more rapid or fluent translation approach. The large variance in fixation durations suggests that some participants engage in frequent, shorter fixations, while others rely on longer fixations to process information. Figure 3: Pupil dilation by participant. Figure 2: Histogram of average pupil dilation. Figure 5 presents boxplots of pupil dilation across AU types (parallel, ST, and TT) for both translation directions (E-C and C-E), highlighting differences in cognitive effort across translation tasks. The results indicate that TT processing exhibits a slightly higher median pupil dilation than ST and parallel processing, suggesting that text production (TT) demands greater cognitive effort than comprehension (ST). In both translation directions, ST processing has a slightly lower median pupil dilation than parallel processing, aligning with the expectation that comprehension (ST) is less cognitively demanding than multitasking (parallel). The spread of dilation values appears consistent across AU types, indicating that cognitive effort varies within each condition but follows a similar distribution. The presence of outliers above 3.5 suggests that some translation segments elicited substantially higher cognitive load, potentially due to increased difficulty, ambiguous sentence structures, or complex lexical choices. Figure 6 displays the distribution of gaze event duration across AU types for both translation directions, offering insights into how visual attention is allocated during different translation tasks. The results show that TT processing has the longest median gaze event duration, reinforcing the idea that text production requires prolonged fixations, likely due to increased cognitive demands. In contrast, ST processing exhibits the shortest gaze durations, suggesting that comprehension is a more fluid process that requires less sustained attention. Parallel processing falls between ST and TT, indicating that multitasking demands more visual attention than ST but less than TT.