Evaluation of head pose features for stress detection and classification

This paper investigates variations in head pose features in response to specific stressors. A proper experiment consisting of neutral and stressful states was performed aiming to cover different types of stress affect. Then, features related to head movements and pose were computationally estimated and analyzed. Towards this direction, facial landmarks were fitted using Active Appearance Models (AAM). Using the 2D AAM facial landmarks, a 3D head pose model was estimated revealing head inclinations. Results indicate that specific stress conditions increase head mobility and mobility velocity, in both translational and rotational features. Even though stress modulates head movements and velocities, the most prominent increases are presented during tasks that include participant's speech. The degree and the intensity of the interaction effect between speech and stress should be investigated in more detail. The analysis reports that specific head pose features can be significant stress indicators that could contribute among other facial cues in reliable stress recognition.