An Empirical Investigation into How Users Adapt to Mobile Phone Auto-Locks in a Multitask Setting

摘要

Auto-locks are a necessary feature on many modern day mobile devices, but can they sometimes have detrimental consequences? In this paper we investigate how auto-locks can affect behavior in a demanding multitasking scenario. A study is conducted in which participants had to enter text using a touch-screen interface while driving a simulated vehicle in a lab setting. Different auto-lock mechanisms were implemented on the secondary device, manipulating both the duration of the lockout threshold (i.e., the period of inactivity before the auto-lock was initiated) and the complexity of the unlock procedure (i.e., how easy it was for the user to unlock the device once it had locked). Results showed that lane-keeping performance on the primary driving task was worse when there was a shorter lockout threshold. The reason for this was two-fold: (1) participants took fewer long pauses between typing actions, so as to avoid being locked out of the device, and (2) when the device did lock, unlocking it took time and further distracted the driver. In support of this latter finding, we also found that a more complex unlock procedure, which required a pin code to be entered, resulted in worse lane-keeping performance than when the device could be unlocked by making a simple button press. These findings suggest that auto-locks can dissuade users from regularly interleaving attention between other ongoing activities. Designers should keep this in mind when incorporating auto-locks in mobile devices.