Push the Red Button: Comparing Notification Placement with Augmented and Non-Augmented Tasks in AR

Visual notifications are omnipresent in applications ranging from smart phones to Virtual Reality (VR) and Augmented Reality (AR) systems. They are especially useful in applications where users performing a primary task have to be interrupted to react to external events. However, these notifications can cause disruptive effects on the performance of users concerning their currently executed primary task. Also, different notification placements have been shown to have an influence on response times, as well as e.g. on user perceived intrusiveness and disruptiveness. We investigated the effects and impacts of four visual notification types in AR environments when the main task was performed (1) in AR and (2) the real world. We used subtitle, heads-up, world space, and user wrist as notification types. In a user study, we interrupted the execution of the main task with one of the AR notification types. When noticing a notification, users responded to it by completing a secondary task. We used a Memory card game as the main task and the pressing of a correctly colored button as the secondary task. Our findings suggest that notifications at a user’s wrist are most suitable when other AR elements are present. Notifications displayed in the World are quick to notice and understand if the view direction of a user is known. Heads-up notifications in the corner of the field-of-view, as they are primarily used in smart glasses, performed significantly worse, especially compared to Subtitle placement. Hence, we recommend to use different notification types depending on the overall structure of an AR system.