Effects of system barge-in responses on user impressions

When designing a spoken dialogue system, in particular a real-time one, not only what the system responds but also when it responds need to be considered. This paper focuses on when the system should appropriately respond with backchannels, and reports an experiment that compared two response-time conditions: the immediate response and the orderly response. The results of the experiment show that the immediate barge-in backchannels can cause some subjects to have negative impressions of the system. This implies that the orderly response strategy is better and less risky than the simple immediate strategy and that some considerations might be required in designing a better barge-in response.