Abstract: A robot or other conversational agent determines whether a human interlocutor has ceded the conversational floor by detecting the absence of a particular speech characteristic such as the introduction of filler speech at the end of an utterance, and the presence of a characteristic physical behaviour, such as the interlocutor returning their gaze to a focal point of the conversion, such as the robots face, during a specified time window after the end of the utterance. Where this combination of characteristics is detected, the robot can determine that the conversational floor is open and that a response may be appropriate. This may trigger a conversational response for example via voice or text.