In a previous job I looked into the viability of pen computing, specifically which companies had succeeded commercially with a pen-based interface.

A lot of folks are too young to know this, but there was a time when it was accepted wisdom that much of personal computing would eventually converge to a pen-based interface, with the primary enabling technology being handwriting recognition.

What I found is that computer handwriting recognition can never ever be good enough to satisfy people's expectations. Why? Because no one is good enough to satisfy most people's expectations for handwriting recognition, including other humans, and often even including themselves!

Frustration with reading handwriting is a given in human interaction. It will be a given in computer interaction too--only, people don't feel like they need to be polite to a computer. So they freely get mad about it.

The companies that had succeeded with pen computing were those that had figured out a way to work around interpreting natural handwriting.

One category was companies who are specialized in pen computing as an art interface--Wacom being the primary example at the time. No attempt at handwriting recognition at all.

The other was companies who had tricked people into learning a new kind of handwriting. The primary example is the Palm Pilot's "Graffiti" system of characters. The neat thing about Graffiti is it reversed customer expectations. Because it was a new way of writing, when recognition failed, customers often blamed themselves for not doing it right!

We all know what happened instead of pens: touchscreen keyboards. The pen interface continues to be a niche UI, focused more on art than text.

It's interesting to see the parallels with spoken word interfaces. I don't know what the answer is. I doubt many people would have predicted in 2001 that the answer to pen computing was a touchscreen keyboard without tactile keys. Heck people laughed about it in 2007 when the iPhone came out.

But I won't be surprised if the eventual product that "solves" talking to a computer, wins because it hacks its way around customer expectations in a novel way--rather than delivering a "perfect" voice interface.