# A Study of Gender Bias in Face Presentation Attack and Its Mitigation
## 4 Experimental Results
### Phase 1: Evaluating Gender Bias in Different CNN-Based Face Presentation Attacks Detection Methods
#### 4.1.1 Exploring Gender Bias Using ResNet50 and Transfer Learning  
This subsection covers the results of three related experiments. ResNet 50's Experiment 1  
It was conducted with the original test dataset that includes 23 males and 10 females with 3 live and 4 spoof videos per subject. According to Table 5, ResNet50 achieved a slightly higher accuracy with women than with men. Females' testing accuracy is 0.99 while males' accuracy is 0.98. EER's value for women is moderately smaller than for men. To a slight extent, FAR, FRR, HTER, and ACER for female samples are also better than for male samples. Moreover, AUC value for females is higher than for males. In terms of FAR and FRR rates women have lower values than males. Figure 8 demonstrates that the values for precision of Class 1 (spoof) and recall of Class 0 (real) are similar for both males and females. However, the values for precision of Class 0 and recall of Class 1 are better for females. Females' f1 scores are also slightly better than males' f1 scores. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Experiment 1**} & \multicolumn{2}{c}{**Experiment 2**} & \multicolumn{2}{c}{**Experiment 3**} \\ \cline{2-7}  & **Males** & **Females** & **Males** & **Females** & **Males** & **Females** \\ \hline \hline  & \multicolumn{6}{c}{**ResNet50’ Results**} \\ \hline Number of Subjects & 23 & 10 & 10 & 10 & 23 & 10 \\ \hline Videos per Subject & 3 live, 4 spoof & 3 live, 4 spoof & 3 live, 4 spoof & 3 live, 4 spoof & 3 live, 4 spoof & 6–7 live, 8–9 spoof \\ \hline Number of Frames & 104,019 & 46,293 & 46,065 & 46,293 & 104,019 & 94,770 \\ \hline Testing Accuracy & 0.975\% & 0.989\% & 0.975\% & 0.989\% & 0.975\% & 0.997\% \\ \hline EER & 0.037 & 0.018 & 0.038 & 0.018 & 0.037 & 0.003 \\ \hline FAR & 0.00091 & 0.0 & 0.0 & 0.0 & 0.00091 & 0.00009 \\ \hline FRR & 0.056 & 0.024 & 0.056 & 0.024 & 0.056 & 0.004 \\ \hline HTER & 0.028 & 0.012 & 0.028 & 0.012 & 0.028 & 0.002 \\ \hline APCER & 0.0 & 0.0 & 0.0 & 0.0 & 0.0 & 0.0 \\ \hline BPCER & 0.057 & 0.024 & 0.057 & 0.024 & 0.057 & 0.005 \\ \hline ACER & 0.028 & 0.012 & 0.028 & 0.012 & 0.028 & 0.0025 \\ \hline AUC & 0.98 & 0.99 & 0.979 & 0.99 & 0.98 & 0.997 \\ \hline \hline  & \multicolumn{6}{c}{**VGG16’ Results**} \\ \hline Number of Subjects & 23 & 10 & 10 & 10 & 23 & 10 \\ \hline Videos per Subject & 3 live, 4 spoof & 3 live, 4 spoof & 3 live, 4 spoof & 3 live, 4 spoof & 3 live, 4 spoof & 6–7 live 8–9 spoof \\ \hline Number of Frames & 104,019 & 46,293 & 46,065 & 46,293 & 104,019 & 94,770 \\ \hline Testing Accuracy & 0.97\% & 0.99\% & 0.97\% & 0.99\% & 0.975\% & 0.997\% \\ \hline EER & 0.043 & 0.018 & 0.049 & 0.018 & 0.037 & 0.003 \\ \hline FAR & 0.033 & 0.015 & 0.039 & 0.015 & 0.00091 & 0.00009 \\ \hline FRR & 0.006 & 0.002 & 0.008 & 0.002 & 0.056 & 0.004 \\ \hline HTER & 0.019 & 0.008 & 0.023 & 0.008 & 0.028 & 0.002 \\ \hline APCER & 0.0 & 0.0 & 0.0 & 0.0 & 0.0 & 0.0 \\ \hline BPCER & 0.006 & 0.002 & 0.008 & 0.002 & 0.057 & 0.005 \\ \hline ACER & 0.003 & 0.001 & 0.004 & 0.001 & 0.028 & 0.0025 \\ \hline AUC & 0.975 & 0.989 & 0.971 & 0.989 & 0.98 & 0.997 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Results for experiments in phase 1. ResNet 50's Experiment 2  
The second test dataset, which contains ten subjects for each gender with three live and four spoof videos per subject, was used in this experiment. The number of male subjects tested was reduced to 10 subjects from 23 subjects. The reason behind this modification is to create some balance in the test data, and observe if the differences in results between women and men in experiment1 is due to the unevenness of the number of test subjects from both gender. However, the males and females' accuracies after the modification are similar to those in experiment 1. Table 5 shows that EER, HTER, ACER, and AUC values did not change, and women are still slightly surpassing men. The classification report in Figure 9 shows that the results for precision and recall for both males and females are similar to the ones in experiment 1.