A robot's appearance and behavior provide cues fa the robot's abilities andpropensities. We hypothesize that an appropriate match befween a robot's social cues and its task will improve people's acceptance of and cooperation with the robot. In an experiment, people systematically prefeved robots f o r jobs when the robot's humanlikeness matched the sociability required in those jobs. In two other erperiments, people complied more with a robot whose demeanor matched the seriousness of the task

HRI researchers interested in social robots have made large investments in humanoid robots. There is still sparse evidence that peoples' responses to robots differ from their responses to computer agents, suggesting that agent studies might serve to test HRI hypotheses. To help us understand the difference between people's social interactions with an agent and a robot, we experimentally compared people's responses in a health interview with (a) a computer agent projected either on a computer monitor or life-size on a screen, (b) a remote robot projected life-size on a screen, or (c) a collocated robot in the same room. We found a few behavioral and large attitude differences across these conditions. Participants forgot more and disclosed least with the collocated robot, next with the projected remote robot, and then with the agent. They spent more time with the collocated robot and their attitudes were most positive toward that robot. We discuss tradeoffs for HRI research of using collocated robots, remote robots, and computer agents as proxies of robots.

A conversational robot can take on different personas that have more or less common ground with users. With more common ground, communication is more efficient. We studied this process experimentally. A "male" or "female" robot queried users about romantic dating norms. We expected users to assume a female robot knows more about dating norms than a male robot. If so, users should describe dating norms efficiently to a female robot but elaborate on these norms to a male robot. Users, especially women discussing norms for women, used more words explaining dating norms to the male robot than to a female robot. We suggest that through simple changes in a robot's persona, we can elicit different levels of information from users-less if the robot's goal is efficient speech, more, if the robot's goal is redundancy, description, explanation, and elaboration.

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Human-robot interaction could be improved by designing robots that engage in adaptive dialogue with users. An adaptive robot could estimate the information needs of individuals and change its dialogue to suit these needs. We test the value of adaptive robot dialogue by experimentally comparing the effects of adaptation versus no adaptation on information exchange and social relations. In Experiment 1, a robot chef adapted to novices by providing detailed explanations of cooking tools; doing so improved information exchange for novice participants but did not influence experts. Experiment 2 added incentives for speed and accuracy and replicated the results from Experiment 1 with respect to information exchange. When the robot's dialogue was adapted for expert knowledge (names of tools rather than explanations), expert participants found the robot to be more effective, more authoritative, and less patronizing. This work suggests adaptation in human-robot interaction has consequences for both task performance and social cohesion. It also suggests that people may be more sensitive to social relations with robots when under task or time pressure.