HCI Theory, Education and Practice -- Human-Computer Natural Interaction Design Practice Based on Unconscious Design Concept -- Implementation of Lean Product Development in a University Course and an Industry Project: Lessons Learned from a Comparative Study -- Human Computer Interacting through a Game Engine: Qualifying Inclusive Design in Architecture -- Human-Computer Interaction in Education: Keyword and Discipline Network in 20 years -- Building Common Ground: Applying Mutual Learning in the UI/UX Education -- Smart Speakers for Inclusion: how can Intelligent Virtual Assistants Really Assist Everybody? -- A Panel to Confront the Differences in Intersectional HCI -- Information Differentiation in the Information Society: From the Perspective of all Stages of Human Information Activities -- Machine-Human Interaction: A Paradigm Shift? -- Understanding Agency in Human-Computer Interaction Design -- Grounding of Concept, Indexical and Name -- Ethics in Human-Centered Design -- AI Creativity and The Human-AI Co-Creation Model -- Two-Way Human-Agent Trust Relationships in Adaptive Cognitive Agent, Adaptive Tasking Scenarios: Literature Metadata Analysis -- A Review of Multimodal Interaction in Intelligent Systems -- An Unheimlich Media: Bringing the Uncanny into the World -- Implementation Goals for Multimodal Interfaces in Human-Computer Interaction -- UX Evaluation Methods, Techniques and Tools -- Guidelines for Collecting Automatic Facial Expression Detection Data Synchronized with a Dynamic Stimulus in Remote Moderated User Tests -- Distributed Remote Psychophysiological Data Collection for UX Evaluation: A Pilot Project -- A Chatbot Solution for eGLU-box Pro: The Usability Evaluation Platform for Italian Public Administrations -- ERM-AT Applied to Social Aspects of Everyday Life -- Civil Aircraft Cockpit Human Machine Interactive Dynamic Assessment Quality Improvement based on System Engineering -- Is Usability Evaluation of DSL Still a Trending Topic? -- A Sentiment Analysis Web Platform for Multiple Social Media Types and Language-Specific Customizations -- FLM-2A: Towards Automated HCI Modeling of Android Applications based on a Modified Version of the Keystroke Level Model -- Quality in Use -Case Study for Evaluation -- How to Evaluate a Good Conversation? An Evaluation Framework for Chat Experience in Smart Home -- Collaborative Heuristic Inspection: Evaluator Experiences and Organization of Work -- Emotional and Persuasive Design -- Blossoms: Preliminary Experiment on Sharing Empathy Online -- An Emotional Tactile Interaction Design Process -- Continuous Monitoring of Interactive Exhibits in Museums as Part of a Persuasive Design Approach -- Engaging New Residents' City Exploration Using a Gamified Location-Based Information Interactive System -- The Impact of Facial Attractiveness and Affective Person Knowledge on Visual Awareness -- Integrating SSTQUAL, Kano Model and Attractiveness Engineering to Analyze User's Emotional Needs in Self Check-in Service -- Technological Influence on Self-esteem: Towards a Research Agenda through a Systematic Literature Review -- Research on Emotional Design of Visual Interaction based on Cognitive Psychology -- Comparison of Kawaii Feelings for Magnets with Different Shapes between 2007 and Present -- Comparison of Color Features of Kawaii Fashion Styles in Japan -- Emotions and Cognition in HCI -- Voice Switching in Voice-Enabled Digital Assistants (VDAs) -- Facial Emotion Recognition in UX Evaluation: a Systematic Review -- Analysis of Emotion in Socioenactive Systems -- Affective Robot Learner: Implementation of Artificial Emotion System Inspired by Educational Psychology -- Effect of Shifting Own Hand Position in Virtual Space on Mental Body Model -- Rehabilitation Aims and Assessed Brain Activity by Means of Brain-Computer Interfaces in People in a Vegetative State- Preliminary Results -- Online Classification of Cognitive Control Processes using EEG and fNIRS: a Stroop Experiment -- A New Algorithm to Find Isometric Maps for Comparison and Exchange of Facial Expression Perceptions -- Definition and Estimation of Dimension in Facial Expression Space -- Mobile Multitasking in Urban Contexts: Habituation and Countermeasures -- Automatic Recognition of Experienced Emotional State from Body Movement.

The three-volume set LNCS 12762, 12763, and 12764 constitutes the refereed proceedings of the Human Computer Interaction thematic area of the 23rd International Conference on Human-Computer Interaction, HCII 2021, which took place virtually in July 2021. The total of 1276 papers and 241 posters included in the 39 HCII 2021 proceedings volumes was carefully reviewed and selected from 5222 submissions. The 139 papers included in this HCI 2021 proceedings were organized in topical sections as follows: Part I, Theory, Methods and Tools: HCI theory, education and practice; UX evaluation methods, techniques and tools; emotional and persuasive design; and emotions and cognition in HCI Part II, Interaction Techniques and Novel Applications: Novel interaction techniques; human-robot interaction; digital wellbeing; and HCI in surgery Part III, Design and User Experience Case Studies: Design case studies; user experience and technology acceptance studies; and HCI, social distancing, information, communication and work.