"Why did this voice agent not understand me?": error recovery strategy for in-vehicle voice user interface

We aimed at investigating the effects of error recovery strategy that could enable the drivers to recover from the non-understanding error when interacting with the in-vehicle voice user interface (VUI). An experiment using a driving simulator was conducted with forty-seven participants who performed driving tasks with the VUI. One of three different error recovery strategies (ask repeat, re-prompt, and you can say) was suggested to recover from the non-understanding errors. A subjective questionnaire and semi-structured interviews were used to collect the participants' workload, perceived reasons for errors, and preference. Results showed participants felt that 'you can say' was more difficult than the 're-prompt' condition. However, preferences of 'ask repeat' and 'you can say' were significantly higher than 're-prompt' because the perceived reason for the non-understanding was 'input error' when the system used the 're-prompt' method. These findings provide insights into the design of the VUI in the context of driving.