Shoulder surfing remains a liability to the security of private data on mobile phones, even as secondary biometric authentication becomes more commonplace. Mobile users in public or shared spaces may therefore shield their screen from external viewers (and themselves) while unlocking. However, this coping strategy can lead to difficult and inaccurate entry. We are conducting a study characterizing this type of interaction and examining the efficacy of a tactile aid to support spatial

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... to the interface, with the aim of augmenting out-of-view PIN and graphical pattern unlocking. Preliminary findings suggest the tactile channel may support eyes-free unlocking, but requires careful integration. We also propose an initial set of qualitative codes addressing user strategies employed for out-of-view interaction.