Is Fitts’ Law redundant in the post-mouse world?


Fitts' Law, in it's simplest form, is a way of calculating the speed of use and usability of an item such as a button based on:
  1. how far away you are from the button and??
  2. the size of the button.??

When you think about it, it's logical that if a button is closer and has a larger hit state, it 's more usable than a button which is a long way away and is smaller – the eyes and handtake longer to slow down and focus on hitting the smaller state at the end of a journey where they may have been moving at some speed.??

However, how relevant is this on an iPad, and how do we measure it? To start with, the idea of 'my pointer' at a start point is harder to quantify because we may tend to use the iPad with all fingers rather than one, almost more like a keyboard. Even if we are only using one finger, this will always be quicker than a mouse, where your eyes and mind are first locating the mouse's start position, making some (however short) leap from eyes to brain to hand to mouse moving on screen. If apps are consistent in their design this helps, as on the desktop; all buttons are uniform size, shape and location (arranged on a grid).


It would be interesting to do some studies with users, arranging icons on a Mac desktop and icons on an iPad desktop to measure Fitts Law as a comparison. In Mac OS we can even increase the size of the dekstop file icons.

Finally, I'm guessing Fitts Law may also become less of a factor given other interface types we are seeing – mobile phones with various buttons as well as the touchscreen, Microsoft's Kinect gestural interface for the Xbox (although I'm sure this will throw up a whole heap of other usability challenges), voice controls…
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