The majority of studies developed to recognize human emotions are limited to a single modality, namely, facial expressions or speech. This book introduced a multimodal approach to improve the accuracy of the emotion recognition by combining audio and visual data. Furthermore, a CNN model has been proposed to automatically extract facial features that uniquely differentiate facial expressions, and this method has been applied to recognize the cognitive states of learners in E-learning environments, and the learners' facial expressions are mapped to cognitive states such as boredom, confusion,...