A Multimodal Positive Computing System for Public Speaking - Evaluating User Responses to Avatar and Video Speaker Representations Topics: Interactive Systems for Education and Training; Multimodal Systems and Application; Usability and User Experience In Proceedings of the 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications - Volume 3 IVAPP: VISIGRAPP, 38-43, 2018 , Funchal, Madeira, Portugal