People's expectation on the use of pragmatic inferences in “robot utterances”

People’s utterances often mean information that is not stated in the utterance itself. For example, if you invited your friends Naomi and Ken for party and another good friend said, “Naomi will come,” people may assume that Ken will not come. The reason is that if Ken will also come, your friend would have said so, thus, not saying may mean that he will not come. This kind of inference is called pragmatic inference and assumed to be important for human communication. Then do we assume communicative robots use such pragmatic inferences? This study examined whether people think robots’ utterances include certain types of pragmatic inferences when people interacted with robots via virtual reality who appeared to be autonomous/non-autonomous and produced considerate words/no considerate words, in addition to human avatar. The result was that when the implicature task was more ambiguous, participants thought the human avatar with considerate words, the autonomous robot with considerate words, and the non-autonomous robot without considerate words would use similar implicature (“ad hoc implicature”). However, participants’ expectation for the autonomous robot without considerate words was more varied. This difference was not found when the task was more ad-hoc implicature inclined. The study suggests that people may assume different types of implicature for robots according to the robot types.