PAR

While drinking water, do not forget those who dug the well. — Chinese proverb To my parents and all my teachers Acknowledgements Towards finishing this thesis, I would like to express my deepest gratitude to my advisor Dr. Pearl Pu. Without her effort, I could never have encountered such an interesting and challenging research project. When I look back at the four years in HCI Group, I am amazed how she has helped me identify my strength and uncover my potentiality. She skillfully guided me to master all essential skills in multi-disciplines as an HCI researcher. My sincere appreciation for her encouragement when I was down and proposing more challenging goals when I conquered the previous one. I feel so fortunate to have her as my advisor! My sincere gratitude also goes to Swiss National Science Foundation for generously sponsoring this exciting research project for the four years. I would like to thank my jury members – Prof. Emre Telatar, Dr. Denis Gillet, Prof. Antoin