The Importance of Timing—An Expert Evaluation on Latencies for Voice Assistants

In a driving simulator study, six experts interacted with an in-vehicle voice assistant (VA) and rated different latencies. The results suggest that in order to maintain drivers’ satisfaction with the interaction, in-vehicle VAs should have a latency of no more than 5 s. A slight delay of 1.5 s was rated best while shorter latencies caused highest variance amongst experts—indicating that the fastest response may not necessarily be the most desirable. Satisfaction may also depend on the complexity of the use case as experts showed higher tolerance toward longer latencies in the navigation-domain. Furthermore, our results raise thought-provoking insights about the importance of considering human expectations and preferences in the design of in-vehicle VAs. Despite technological advancements, humans might still expect a natural delay, similar to that in a human-human interaction. These findings emphasize the need to balance using cutting-edge technology with the desire for familiar interactions.