The theme of the 4th Doctoral Symposium on Human Centered Computing (Human-2026) is to explore cutting-edge research that advances understanding of humans in computational contexts and drives innovations in human-centered technologies. It emphasizes interdisciplinary exchange among PhD students, postdoctoral researchers, and early-career industry R&D professionals, highlighting work that bridges human behavior, usability, interaction, and information processes. Through presentations and discussions, participants will engage with peers and international experts to refine ideas, foster collaboration, and contribute to the evolving foundations and applications of human-centered computing.