Thursday, June 21, 2007

Deckard's Rules for VUI Development

In my last post I raved about the great science fiction movie Blade Runner. Based on the some of the issues raised in the movie, I'd like to propose (only partly in jest) Deckard's Rules for VUI Development. The rules are named for the character Deckard rather than Tyrell because (1) Tyrell got it wrong and (2) Deckard had to clean up the mess.

Rule 1: Don't over-engineer your system
Replicants Roy and Leon were built as fighters, presumably to protect property on off-world colonies. They were also created smarter and stronger than humans, and could pass for humans on Earth. Is it a good idea to build autonomous agents that are smarter and stronger than you and give them the capacity and motive to kill? No. It's a bad idea. Build your VUI system to do what its users need it to do and nothing more. And don't try to build something that could pass for a human.

Corollary to Rule 1: Keep your eye on the ROI
The technically sophisticated replicants were designed to self destruct after four years on fears that they could develop uncontrollable feelings and emotions if allowed to live any longer. Replacing advanced technology is extremely expensive - better to build your system to last, and maintain it as needed.

Rule 2: Words are powerful shapers of behavior - be brief and to the point
Deckard and Sebastian were manipulated into doing what others wanted them to do; Deckard into chasing replicants and Sebastian into setting a meeting between Roy and Tyrell. The dialogs required to do this were terse but gave sufficient direction to the targets that they understood what needed to be done. Good VUI dialogs are short and give users direction on what they need to say, without resorting to the painful "In order to do x, say x" construction.

Rule 3: Our methods for evaluating advanced technology isn't good enough - we need better tools
The Voight-Kampff test for determining whether a subject was replicant or human was nearly obsolete. It took Deckard, a trained evaluator, 100 questions to determine Rachael's identity. Our evaluation methods for VUIs are in a similar state. We still mostly rely on usability testing and questionnaires that were developed to evaluate web pages and GUIs. I gave a presentation at a UPA workshop in 2002 and pointed out that our old usability test protocols aren't sufficient for evaluating things like autonomous agents and speech systems. We need better evaluation methods.

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