Different types of errors can occur in Conversational User Interfaces (CUIs) like non- or misunderstandings or errors in connected APIs. Handling such problems with meaningful responses that help the user recover and continue the conversation with the system is important to include in the conversation design. This is often called “fallback” or “fallback responses”. Bad error recovery will lead to failed interactions with the system and unhappy users that will likely not use the system again. Good error handling is something that often does not gets the attention that it needs from my point of view both in research and in commercial projects.
One exception that I would like to share here is the paper “Progressivity for Voice Interface Design” [1] explores the usage of progressivity to prevent people from getting stuck at a certain point in a conversation using Amazon Alexa as an example use case. The idea behind “progressivity” is that the responses are designed in such a way that the user always gets enough information to continue the task. Generic default fallbacks are perceived as non-answers and impede progress because users tend to ask almost the same question again in such cases resulting in another default fallback response [1]. When you include additional information or an indication of the error, even a vague one like “Sorry I could not understand what you said.”, users will likely reformulate their input [1]. However, there is a trade-off between potentially helpful information and simplicity [1].
It is to point out here that error handling and the overall response design of a CUI system are highly related because if the system and user expectations differ e.g. about how to continue the conversation, it occurrence of a misunderstanding is way higher.
Examples
A constructed example.
System: “Welcome to the example banking bot. What can I do for you?”
User: “what can you do for me?”
System: “Sorry. I did not understand that. Could you rephrase it please?”
Better: I can help you to perform transactions, to view your account balances, and I can try to answer your questions about our products. What do you want to do?
Another alternative would be to also provide buttons for the most common functions in such a fallback response.
For more inspiration about error handling and recovery, I can also recommend the corresponding chapters in the books by Michael F. McTear [2] and Cathy Pearl [3].
References
[1] Joel E. Fischer, Stuart Reeves, Martin Porcheron, and Rein Ove Sikveland. “Progressivity for Voice Interface Design”. “1st International Conference
on Conversational User Interfaces (CUI 2019)” (2019). DOI:http://dx.doi.org/10.1145/3342775.3342788
[2] Michael Mctear, Zoraida Callejas, and David Griol. 2016. The Conversational
Interface. DOI:http://dx.doi.org/10.1007/978-3-319-32967-3
[3] Cathy Pearl. 2016. Designing voice user interfaces: principles of conversational
experiences. ” O’Reilly Media, Inc.”.