## 2 Related Works
### Notification Management Concepts  
Notification management can be defined from different perspectives. For example, IT systems can be developed upon pre-set notification management policies [30] or based on the dynamic context of use across various smart devices [31]. Dynamic context may refer to various important detectable conditions, such as temporal settings in which time plays a crucial role in the receptivity of push notifications [32]. Location-aware triggered push notifications have also been shown to be a way of increasing engagement and attention [33]. However, situations such as activity-related contexts have also been shown to influence user responses with regard to push notifications [34]. The current study understands notification management as actions by the users in order to avoid disruptions while trying not to miss out on the relevant information. Distinct patterns in such actions in turn refer to notification behavior. Focusing on smartphones, users are provided with various tools for managing their notifications. These tools follow different logic and reasoning, which the authors define as notification management concepts. Most simple examples are putting the phone in a \"silent\" or \"do not disturb\" mode. Due to the complexity of smartphone functionality, even these simple concepts are not as simple as they may seem. For example, phone alarms bypass silent mode: many users may have encountered a situation where, despite the phone being silenced, the alarm went off in a silent situation. The simplest concepts of notification management are often not enough to satisfy the more complex needs of the users. Similar exceptions apply to headphones or other sound widgets. These examples indicate the need for more complex notification management in order to deal with disruptions. [PERSON] brought out four primary methods for coordinating interruptions of users from their focus: immediate, negotiated, mediated, and scheduled [35]. [PERSON] also proposed a taxonomy of the problem of user interruption with eight major dimensions: source of interruption, an individual characteristic of the person receiving interruption, method of coordination, meaning of interruption, method of expression, channel of conveyance, human activity changed by interruption, and effect of interruption [36]. While interruptions in [PERSON]'s research are related to safety critical user interfaces (UI) in aviation, the authors believe this knowledge could also apply to smartphone notification management concepts. A variety of attempts, in the form of intervention methods, have been undertaken to mitigate the negative effects push notifications have on smartphone users. The focal point of many of these approaches was predicting suitable moments to interrupt users based on user data. Intelligent notification management strategies that take into account user preferences, event severity, or schedules to lessen the need for users to deliberately ignore or snooze notifications are one [37]. Batching notifications showed results in maintaining the usefulness of being notified while also diminishing the negative unpredictability association [38]. Determining opportune moments to deliver timely information requires a coherent understanding of users' external factors. These require attention from the user and end up disrupting their workflow which can have negative consequences on the overall smartphone push notification experience [39]. When the number of such disruptions in the form of push notifications becomes abundant, interruption overload occurs with detrimental effects on users. Several approaches have been applied to minimize such adverse effects. Within the human-computer interaction domain, one of these is called interruptibility, where intelligent systems help provide contextually appropriate and timely moments of sending a push notification. [PERSON] et al. [40] have stated potential benefits and desirable outcomes that intend to remove the frustration and reactive burden on users by doing so.