Secure authentication on situated displays (e.g., to access sensitive information or to make purchases) is becoming increasingly important. A promising approach to resist shoulder surfing attacks is to employ cues that users respond to while authenticating; this overwhelms observers by requiring them to observe both the cue itself as well as users' response to the cue. Although previous work proposed a variety of modalities, such as gaze and mid-air gestures, to further improve security, an understanding of how they compare with regard to usability and security is still missing as of today. In this paper, we rigorously compare modalities for cue-based authentication on situated displays. In particular, we provide the first comparison between touch, mid-air gestures, and calibration-free gaze using a state-of-the-art authentication concept. In two in-depth user studies (N=37) we found that the choice of touch or gaze presents a clear trade-off between usability and security. For example, while gaze input is more secure, it is also more demanding and requires longer authentication times. Mid-air gestures are slightly slower and more secure than touch but users hesitate to use them in public. We conclude with three significant design implications for authentication using touch, mid-air gestures, and gaze and discuss how the choice of modality creates opportunities and challenges for improved authentication in public. CCS Concepts: • Security and privacy → Authentication; • Human-centered computing → Human computer interaction (HCI); Interaction techniques; Interaction design;

Figure 1. We explore whether field studies on public displays can be conducted in virtual reality. In two user studies we compare user behavior between a real public space (left) and a virtual public space (middle). For one study, we developed a gesture-controlled display for both environments (right).

Abstract-Mid-air gestures have been largely overlooked for transferring content between large displays and personal mobile devices. To fully utilize the ubiquitous nature of mid-air gestures for this purpose, we developed SimSense, a smart space system which automatically pairs users with their mobile devices based on location data. Users can then interact with a gesturecontrolled large display, and move content onto their handheld devices. We investigated two mid-air gestures for content transfer, grab-and-pull and grab-and-drop, in a user study. Our results show that i) mid-air gestures are well suited for content retrieval scenarios and offer an impressive user experience, ii) grab-and-pull is preferred for scenarios where content is transferred to the user, whereas grab-and-drop is presumably ideal when the recipient is another person or a device, and iii) distinct gestures can be successfully combined with common point-and-dwell mechanics prominent in many gesture-controlled applications.

Patients who receive 5α-reductase inhibitors have improved disease specific survival after bladder cancer diagnosis compared to those who do not receive them while α-blockers were not associated with survival. This supports the benefits of 5α-reductase inhibitors in bladder cancer.

We present Pocket Transfers: interaction techniques that allow users to transfer content from situated displays to a personal mobile device while keeping the device in a pocket or bag. Existing content transfer solutions require direct manipulation of the mobile device, making interaction slower and less flexible. Our introduced techniques employ touch, midair gestures, gaze, and a multimodal combination of gaze and mid-air gestures. We evaluated the techniques in a novel user study (N=20), where we considered dynamic scenarios where the user approaches the display, completes the task, and leaves. We show that all pocket transfer techniques are fast and seen as highly convenient. Mid-air gestures are the most efficient touchless method for transferring a single item, while the multimodal method is the fastest touchless method when multiple items are transferred. We provide guidelines to help researchers and practitioners choose the most suitable content transfer techniques for their systems.