"What you think is private is no longer" - Investigating the Aftermath of Shoulder Surfing on Smartphones in Everyday Life through the Eyes of the Victims

This paper investigates how experiencing shoulder surfing impacts smartphone users: Through an in-depth survey in the UK (N=91), we specifically investigate how shoulder surfing affects (a) the privacy perceptions of victim users and (b) their interactions with smartphones. We found that the impact of being shoulder-surfed is highly individual. First, shoulder surfing is perceived as unavoidable and frequently occurring, leading to an increased time to complete tasks. Second, users are concerned about their own and other people’s privacy and even consider shoulder surfing a gateway to more serious threats (e.g., identity or device theft). Users are willing to alter their behaviour and use software-based protective measures to prevent shoulder surfing. Finally, we captured a set of user-defined criteria essential to software-based protective measures. Based on our results, we discuss future work directions for user-centred shoulder surfing mitigation.