Results of experiment 2. Achieved results for the second experiment we conducted for the ChimpZoo dataset (A) and the ChimpTaï dataset (B). Again, the black solid line denotes the line of equal error. The green dash-dotted line shows the result for globally extracted Gabor features in combination with LPP and SRC. The red dashed line denotes the results for the local SURF descriptors extracted around six facial feature points. Each feature vector was transformed separately into a smaller dimensional subspace using LPP before classifying the concatenated final feature vector using a SVM with an RBF kernel. Although the locally extracted features perform worse than the global descriptor, they carry important information for classification. This can be seen from the results of the decision fusion scheme (blue solid line) that outperforms algorithms based on global and local features alone with an EER of 0.1189 and 0.2669 for the ChimpZoo and the ChimpTaï dataset, respectively.