  This paper explores the concept of engagement, the process by which
individuals in an interaction start, maintain and end their perceived
connection to one another. The paper reports on one aspect of engagement among
human interactors--the effect of tracking faces during an interaction. It also
describes the architecture of a robot that can participate in conversational,
collaborative interactions with engagement gestures. Finally, the paper reports
on findings of experiments with human participants who interacted with a robot
when it either performed or did not perform engagement gestures. Results of the
human-robot studies indicate that people become engaged with robots: they
direct their attention to the robot more often in interactions where engagement
gestures are present, and they find interactions more appropriate when
engagement gestures are present than when they are not.
