In addition to Fitts’ Law, we (Schmidt, Zelaznik, Hawkins, Frank & Quinn, 1979) proposed a linear speed-accuracy trade-off. These two laws appear to be fundamentally different. We have begun a series ...

Redditor frendolargo used a principle called Fitts' law to organize his or her own Apple Watch — and followed up the experiment by posting the results in the Apple Watch subreddit. How thoughtful!