I've been watching with interest as designers of all kinds continue to talk themselves out of simple dialogue solutions. To begin this blog sequence on questions, here's a quick primer on three common approaches to VUI scripting:

Indicative or Declarative

• You can say "checking" or "savings".
• You may choose one of these ...
• Options include ...

Imperative

• Please say, "checking" or "savings".
• Make your selection now.
• Please describe, briefly, the reason for your call.

Interrogative

• Checking or savings?
• Do you want to hear that again?
• How may I help you?

To avoid getting embroiled in a linguistic discussion about "moods" and "modals", let's describe these approaches simply as "styles" of scripting—good enough for the art of design if not the science of language.

The third style—the interrogative—constitutes a question. It is easy to describe in guidelines (when in doubt, ask your user a question), and is generally easy in practice to craft. In a spoken dialogue, questions have a lot going for them. They are short. They carry strong turn-taking cues. They call for a reply. And they generate predictable responses, making grammars small and robust.

Whenever you are struggling with the best form for a prompt—whether in directed dialogue or natural language designs—the interrogative is often a good place to start. Just ask a question. Your user will probably give you an answer.