Running with apps: Fitts' law

Studies have shown that walking has a negative effect on input performance on mobile devices. Runners often use their GPS-enabled smartphones to record their exercise, but the effect of running on touch screen input performance has not yet been quantified.

This study aims to fill this gap by performing a Fitts' law experiment on a smartphone. A custom-built Android application was used to measure pointing task performance. Pointing tasks were performed in conditions where participants were either running or stationary, and the device was either handheld in a running armband or worn on the arm in a running armband.

Compared to stationary conditions, running conditions showed higher motion time and lower accuracy. Overall input performance was approximately 47% lower in running conditions, compared to stationary conditions. Furthermore, running speed decreased by 26% when interacting with the device.

Therefore, common interactions while running should be foreseen by developers and designers of mobile applications. And although easier targets contribute to higher input performance, most importantly, the GUI should be forgiving of user error in the typical context of the user.

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