Submitted by I detailed Fitts’ Law not too long ago in one of my usability terms articles (the series will pick up later on, by the way, I am currently too busy with my bachelor’s thesis), and this article is a very detailed addition. It is a little old (October 2007), though. “Back in school, I remember that it wasn’t until I started taking classes in physics that calculus made any kind of real sense to me. I just need diagrams to function. In that spirit, I thought it would be nice to go over Fitts’s Law, a staple in the HCI diet, with a few visuals to explain both the concept and why it’s ideas are a bit more complicated than most would have you believe.”
Thom, are there any studies you are aware of that measure the impact of regular use? In lots of areas of human behaviour, they can be quite unexpected.
The thing I am sceptical about is whether Fitts law (and HIG guidelines generally) really applies if you take account of learning. Is it not possible that the most important feature of how to do something on a computer is whether we have done it that way n times? Take Vi and Emacs, for instance. Completely different, but is there really much difference in productivity after people know them? KDE and Gnome and XP in default modes? I’m thinking of stuff like how in KDE it always prompts for move or copy when you drag and drop. Seems cumbersome at first, but you soon get used to it.
Obviously there are some egregious examples of poor design, requiring you to go through far too many steps, or use tiny obscure buttons with great precision. But leave aside these obvious ones, isn’t it possible that learning is the key factor?
That’s the big weakness of Fitts’, and the reason why its importance should not be overstated: it does not take learning into account.