Chapter 19. Conclusion

The most interesting thing about Radio Rex is that he was a commercial success, a feat that was not repeated in the world of speech technology for many decades. The truth is, you can glean many of the principles in this book just by examining the success of Radio Rex. First, he got the business case right. In 1911, television had not yet been invented, and Radio Rex could keep children happily occupied. That is a major value proposition.

Second, based on a deep understanding of his users their capabilities, limitations, linguistic behaviors, and interests he got the user interface right. It was simple to learn to use: "Just say 'Rex.'" And the persona design was right children loved the little dog.

Third, Radio Rex got the technology right. Simple, one-word recognition was all that was needed (no feature creep here!). It's true that his rejection technology was limited. Rex often responds to any loud sound, not just the word "Rex." For a dog, however, that is probably natural, realistic behavior. In any case, just as the patience of the Schwab system appealed to our first usability subject, the dog's eager, if indiscriminate, responsiveness was a hit with young users.

Rex notwithstanding, VUI design is still a young discipline. We have tried to present the fundamental underpinnings of the discipline and derive best practices in a principled way, supported wherever possible by concrete data and based in all cases on lots of experience. The methodology we present is driven by a number of principles:

• Inform design decisions with end-user input.

• Find solutions that combine business and user goals.

• Avoid expensive changes downstream by focusing on thorough early work.

• Move the design experience close to the user experience so that the designer can conceive of design elements as conversation.

• Make all design decisions with appropriate consideration of context.

The approach to making design decisions is also driven by principles:

• Minimize cognitive load.

• Accommodate conversational expectations.

• Maximize efficiency.

• Maximize clarity.

• Ensure high accuracy.

• Gracefully recover from errors.

It is our hope that you now have a set of valuable best practices that can be applied within an effective methodology. Perhaps more importantly, you should also have an understanding of the underlying fundamentals that you can apply to new situations as they arise.

If we all do our job well, someday we will be able to look back at today's systems the way today we fondly look back at Radio Rex: as a great beginning hinting at vast potential in terms of technology, business value, and, most importantly, user value.