Understanding Image Captioning Models beyond Visualizing Attention
TABLE III: The AUC scores of different explanation methods. L.: LRP, G.: Guided Grad-CAM, Att.: Attention. Higher is better.
['L.-max', 'L.', 'G.-abs', 'Att.', '1− [ITALIC] βt', 'G.']
Guided Grad-CAM is worse because the sign of its scores has no specific meaning. Fixing this by using the absolute value in Guided Grad-CAM-abs results in an improved AUC value. The high AUC value obtained by LRP proves that it identifies the true-positive and false-positive words very well and its sign is informative.