This book constitutes selected papers of the Fourth International Conference on Computer-Human Interaction Research and Applications, CHIRA 2020, held virtually, in November 2020.The 8 full papers presented in this book were carefully reviewed and selected from 44 submissions. The papers selected to be included in this book contribute to the understanding of relevant trends of current research on computer-human interaction, including Interaction design, human factors, entertainment, cognition, perception, user-friendly software and systems, pervasive technologies and interactive devices.