• Emotion recognition and affective interface development unify sensing, interpretation, and generation of emotion in HCI, spanning facial-expression recognition, multimodal cues, and emotion-driven animation [2], [3], [4], [6], [10], [11], [12], [14].

• Affective state measurement and attitudes in computing converge psychometric scales of stress, hassles, anxiety, and trust, illustrating how user affect governs technology interaction [1], [7], [9], [15], [18], [19].

• Computational analysis and representation of facial expressions and smiles underpins recognition and animation research, including spatio-temporal modeling, smiling quantification, and multimodal facial systems [2], [3], [5], [8], [10], [12].

• Language and semantic framing of emotions shape theory and application in HCI, connecting affective semantics to emotion recognition, regulation, and social cognition [9], [13], [14], [16], [17].