## 3 Results
### Psychophysiological Differences According to Pain Intensity  
To examine the impact of pain intensity on psychophysiological responses, participants who selected pain levels of 5, 6, or 7 were categorized into three groups: intensity 5, intensity 6, and intensity 7. A one-way ANOVA was conducted to assess the effect of pain intensity on psychophysiological features, followed by a Bonferroni post hoc analysis (Table 6). In the ANOVA, physiological features were represented by the difference between the painful state and baseline, whereas arousal and valence were used directly without transformation. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Feature** & **Intensity 5** & **Intensity 6** & **Intensity 7** & **F** & **\(p\)** & **Post hoc** \\ \hline Valence & \(-2.71\pm 1.795\) & \(-3.55\pm 0.544\) & \(-3.94\pm 0.245\) & 15.356 & \(<\)0.001 & \(5>6=7\) \\ \hline Arousal & \(2.59\pm 0.795\) & \(3.28\pm 0.649\) & \(3.50\pm 0.799\) & 9.561 & \(<\)0.001 & \(5<6=7\) \\ \hline \(\Delta\)HR (beat/min) & \(-1.31\pm 5.795\) & \(-0.81\pm 6.479\) & \(-0.08\pm 6.288\) & 0.297 & 0.744 & - \\ \hline \(\Delta\)SDNN (ms) & \(8.58\pm 15.909\) & \(-0.49\pm 20.376\) & \(7.11\pm 19.414\) & 2.356 & 0.100 & \(6<7\) \\ \hline \(\Delta\)RMSSD (ms) & \(5.41\pm 10.529\) & \(2.87\pm 14.404\) & \(7.25\pm 16.165\) & 1.056 & 0.351 & - \\ \hline \(\Delta\)pNN50 (\%) & \(4.07\pm 12.176\) & \(2.07\pm 13.583\) & \(6.24\pm 11.447\) & 1.326 & 0.270 & - \\ \hline \(\Delta\)HFnu & \(0.06\pm 0.168\) & \(0.08\pm 0.155\) & \(0.08\pm 0.154\) & 0.100 & 0.905 & - \\ \hline \(\Delta\)LF/HF & \(-0.30\pm 1.024\) & \(-0.36\pm 0.667\) & \(-0.28\pm 0.564\) & 0.150 & 0.861 & - \\ \hline \(\Delta\)BVP (V) & \(-0.06\pm 0.059\) & \(-0.06\pm 0.079\) & \(-0.07\pm 0.069\) & 0.349 & 0.706 & - \\ \hline \(\Delta\)PTT (ms) & \(-3.45\pm 11.566\) & \(-4.64\pm 12.394\) & \(-9.07\pm 10.793\) & 2.361 & 0.099 & \(5>7\) \\ \hline \(\Delta\)RR (breath/min) & \(-0.62\pm 0.824\) & \(-0.78\pm 1.105\) & \(-0.53\pm 0.751\) & 0.877 & 0.419 & - \\ \hline \(\Delta\)SCL (\(\mu\)S) & \(0.00\pm 0.060\) & \(0.08\pm 0.146\) & \(0.11\pm 0.171\) & 3.669 & 0.029 & \(5<7\) \\ \hline \(\Delta\)SCR (\(\mu\)S) & \(0.26\pm 0.388\) & \(0.66\pm 0.905\) & \(1.02\pm 1.135\) & 4.274 & 0.016 & \(5<7\) \\ \hline \(\Delta\)FT (\({}^{\circ}\)C) & \(-0.00\pm 0.369\) & \(-0.00\pm 0.319\) & \(-0.06\pm 0.226\) & 0.691 & 0.503 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: One-way ANOVA and Bonferroni post hoc comparison of psychophysiological responses at different pain intensities. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**AFeature** & \multicolumn{2}{c}{**Pain condition**} & \multicolumn{2}{c}{**Statistics**} \\ \cline{2-5}  & **Non-Painful-Baseline** & **Painful-Baseline** & **t** & \(p\)** \\ \hline \(\Delta\)HR (beat/min) & \(4.90\pm 3.47\) & \(-0.87\pm 6.14\) & \(2.132\) & \(0.034\) \\ \hline \(\Delta\)SDNN (ms) & \(-3.02\pm 13.06\) & \(4.15\pm 19.11\) & \(-3.400\) & \(0.001\) \\ \hline \(\Delta\)RMSSD (ms) & \(-1.02\pm 6.45\) & \(5.02\pm 13.89\) & \(-4.402\) & \(<\)0.001 \\ \hline \(\Delta\)pNN50 (\%) & \(-0.51\pm 7.86\) & \(4.03\pm 12.17\) & \(-3.445\) & \(0.001\) \\ \hline \(\Delta\)HFnu & \(0.05\pm 0.16\) & \(0.08\pm 0.16\) & \(-1.304\) & \(0.194\) \\ \hline \(\Delta\)LF/HF & \(-0.26\pm 0.72\) & \(-0.33\pm 0.74\) & \(0.726\) & \(0.467\) \\ \hline \(\Delta\)RR (breath/min) & \(-0.28\pm 0.75\) & \(-0.68\pm 1.02\) & \(3.426\) & \(0.001\) \\ \hline \(\Delta\)BVP (V) & \(-0.01\pm 0.04\) & \(-0.07\pm 0.07\) & \(8.182\) & \(<\)0.001 \\ \hline \(\Delta\)PTT (ms) & \(-1.17\pm 7.08\) & \(-5.91\pm 11.93\) & \(3.774\) & \(<\)0.001 \\ \hline \(\Delta\)SCL (\(\mu\)S) & \(0.01\pm 0.08\) & \(0.08\pm 0.14\) & \(-4.145\) & \(<\)0.001 \\ \hline \(\Delta\)SCR (\(\mu\)S) & \(0.10\pm 0.52\) & \(0.71\pm 0.96\) & \(-6.164\) & \(<\)0.001 \\ \hline \(\Delta\)FT (\({}^{\circ}\)C) & \(0.08\pm 0.23\) & \(-0.04\pm 0.27\) & \(3.471\) & \(0.001\) \\ \hline \end{tabular}
\end{table}