“…SVM classifier is commonly used for pain detection (e.g., facial expression [30], [22], [24], [27], [34], [29], [30], [39], [49], [52], [53], [54], [50], [87], cry [61], [57], [106], and body movement [117], [118]). Other classifiers that are used for pain detection are Neural Network [18], [60], [87], knearest neighbors [57], [53], and k-means [42]. Such classifiers achieved varying levels of performance in detecting the pain label.…”