Acknowledgements

I would like to thank my advisor, Justine Cassell, for giving me freedom to pursue my interests while making sure that I founded my research on a strong theoretical background. I am grateful for her support and supervision. My thanks to Hiroshi Ishii and Henry Lieberman for the class on Collaboration between People, Computers and Things, where my thesis work started to take shape. I am indebted to my readers Bruce Blumberg and Carl Malamud for guidance on drafts of both my proposal and this document.

Special thanks to the members of the Gesture and Narrative Language Group for their encouragement and great company. In particular I would like to thank my officemate and friend Marina Umaschi for bringing the human factor into the office life and my fellow countryman Kris Thórisson for the humor and long nostalgic conversations over sandwiches at the local coffee franchise.

This work would not have been possible without the sponsorship of a number of companies. I would especially like to mention Intel for donating the hardware and Microsoft and TGS for donating the software.

Thanks to my housemate Brygg Ullmer for making me feel at home.

Thanks to my family for life and love.

Thanks to Deepa for being a good supportive friend, and for showing me that avatars can only go so far…