## 2 Review of Related Literature and Applications
### Review of Approaches for Regulating Smart Device Usage
#### 2.2.3 Technology-Based Interventions  
In response to the practical limitations of parent-led approaches, technology-based interventions have emerged as alternative or complementary strategies for regulating smart device use. These interventions leverage system functionalities, dedicated applications, or intelligent algorithms to promote healthier digital habits with reduced dependence on direct parental supervision [35].  
Recent literature classifies these interventions into four subtypes:  
* Restrictive Interventions These approaches enforce rules automatically through features such as screen-time limits, content blocks, or device locks [36]. While these measures establish clear boundaries, they rely on external control and may impede the development of intrinsic self-regulation. Consequently, children may exhibit resistance or engage in compensatory behaviour once restrictions are lifted [37; 38].
* Behavioural Nudging Interventions Behavioral nudges involve subtle interface adjustments or system cues that guide user behaviour without limiting choice. Examples include grayscale display settings, timed reminders for breaks, or reward mechanisms tied to activity completion [39; 40].  
These strategies align with user-centred and persuasive design principles; however, their effectiveness often depends on users' motivation and willingness to engage.
* Environment-Integrated Interventions These strategies connect digital regulation with the user's physical and social context--for example, by establishing screen-free zones, implementing Internet-of-Things-supported sleep routines, or delivering parental education programmes [23]. While such approaches are conducive to long-term behavioural change, they may exert limited immediate impact.
* Artificial-Intelligence (AI)-Based Adaptive Interventions Just-in-time adaptive interventions use real-time data to deliver personalised, context-aware prompts aimed at reducing screen time [41]. Although promising, these systems are primarily designed for adolescents or adults and remain underdeveloped for preschool-aged children [32; 42].  
Overall, although technology-based interventions offer scalable solutions, many still rely on externally imposed rules and do not fully account for young children's developmental needs. These limitations underscore the importance of UX approaches that prioritise affective, developmentally appropriate interactions while actively supporting the cultivation of self-regulation.  
In summary, previous research has introduced various intervention strategies--including parental control, co-use, and technology-driven methods--that collectively provide a valuable conceptual foundation for managing smart device use among young children. However, the implementation of these strategies in real-world contexts--particularly within commercial applications--often diverges from their original design, intent, and developmental focus. Although many tools inspired by these models have been adopted by technology companies and mobile service providers, their effectiveness in fostering intrinsic self-regulation remains uncertain. The following section explores how these strategies have been operationalised in practice, highlighting both their key strengths and ongoing limitations.