Harnessing the "ambience" of the mobile-phone lockscreen for ultra-lite logging.

Increasingly people use mobile phones many times daily. This makes the phoneu0027s lockscreen almost ambient , part of everyday life. This work explores how to use that valuable ambience of the lock-screen to help people maintain awareness of, and to track an important goal, such as improving nutrition. We describe the design of FIT, a lockscreen app for ultra-lite logging of vegetable serves consumed each day. Our 4-week field study of FIT, with 19 young adults indicates it is quick and easy to use. The 973 log events took an average of 1.03 seconds, compared with 0.72 seconds for the 25,530 unlocks. The study demonstrated that most people found FIT to be an ambient reminder to eat vegetables and track intake. Our contributions are the definition of lock-screen ambience and the design and evaluation of FIT, an app that harnesses lockscreen ambience to raise awareness of, and support ultra-lite logging of, an important nutrition goal.