Mobile phone distraction is a critical global road safety issue, contributing to crashes and subsequent injuries and fatalities. This issue has led to calls for effective interventions. Based on neuropsychological research indicating that colour stimuli play a significant role in driving phone engagement, one potential strategy to reduce road user phone use while on the road is activating greyscale on phones. By removing colour, the sensory reward associated with phone use may be diminished, potentially reducing usage. However, this approach has yet to be empirically tested. As such, the aim of this study is to investigate how greyscale influences phone use behaviours while driving and walking. Participants were asked to switch their phone interface from colour to greyscale for a duration of 2-weeks. A mixed-methods approach, including surveys and interviews, was employed to gather insights from participants regarding their perceptions of greyscale on their phone use behaviour while driving and walking. The quantitative results showed that greyscale decreased the frequency of participants glancing at their phone screens in a cradle while driving. However, using the greyscale feature did not lead to significant changes in the frequency of participants picking up the phone and looking at the screen while driving, nor did it increase participants’ use of other devices such as the in-vehicle infotainment system, smartwatches, or voice commands. Additionally, greyscale significantly reduced the probability of pedestrians using handsfree phones while walking, although greyscale did not influence the likelihood of looking at the screen of a handheld phone. The qualitative results revealed that the greyscale had a complex impact on road users’ phone behaviour. Greyscale altered how they used their phones, made them less appealing and enjoyable, and added complexity to phone use. However, some participants found work-around, though not everyone adopted them. Overall, the findings suggest that while greyscale effectively reduced some phone-related behaviours over a 2-week period, its impact on phone use behaviours while driving or walking was limited in scope, with mixed effectiveness across different contexts and with some users finding work-around.

BACKGROUND: Mobile apps are a popular strategy for reducing mobile phone use and preventing maladaptive mobile phone use (MMPU). Previous research efforts have been made to understand the features of apps that have the potential to reduce mobile phone use and MMPU. However, there has been a lack of a comprehensive examination of the effectiveness of such apps and their features. OBJECTIVE: This paper investigated existing apps designed to reduce mobile phone use and prevent MMPU and examined the evidence of their effectiveness. The research aimed to provide a comprehensive analysis of app features that can reduce mobile phone use and MMPU, while also assessing their effectiveness. In addition, we explored users' perceptions of these apps and the various features the apps offer to understand potential adoption issues and identify opportunities. METHODS: This study used 3 methods: a review of scientific evidence, content analysis, and sentiment analysis. RESULTS: Our study comprehensively examine the common features of 13 apps designed to reduce mobile phone use. We extracted and classified the features into 7 types: self-tracking, social tracking, goal setting, blocking, gamification, simplification, and assessment. The effectiveness of these apps in reducing mobile phone use and MMPU varied from weak to strong. On the basis of content analysis, self-tracking and goal setting were the most frequently used features, whereas gamification and assessment were used the least frequently. The intervention strategies that effectively reduce mobile phone use and MMPU included using grayscale mode, app limit features, and mixed interventions. Overall, users tended to accept these apps, as indicated by sentiment scores ranging from 61 to 86 out of 100. CONCLUSIONS: This study demonstrates that app-based management has the potential to reduce mobile phone use and MMPU. However, further research is required to evaluate the effectiveness of app-based interventions. Collaborations among researchers, app developers, mobile phone manufacturers, and policy makers could enhance the process of delivering, evaluating, and optimizing apps aimed at reducing mobile phone use and MMPU.

Maladaptive Mobile Phone Use (MMPU) (also known as Smartphone Addiction, Nomophobia, Fear of Missing Out, or Problematic Mobile Phone Use) is a growing mental health problem. However, the health and safety consequences of MMPU remain unexplored in many real-life contexts. A potential setting where MMPU may have some negative repercussions is on the road. It is well established that road users (e.g., drivers, motorcyclists, pedestrians, and cyclists) increasingly injure themselves or others due to distractions such as phone use while on the road. Emerging research suggests that MMPU is a possible determinant of this risky behaviour. Therefore, it is essential to investigate the relationship between MMPU and mobile phone use behaviour on the road, as it could help guide and improve interventions aimed at increasing road safety. This systematic review investigated the relationship between maladaptive mobile phone use and mobile phone use behaviour on the road in terms of attitudes and risk perception, intention, phone use engagement, performance changes, and safety outcomes. A total of 44 studies were identified with 47 unique samples of road users, of which 68.1% (32/47) were comprised of drivers, 19.1% (9/47) were pedestrians, 8.5% (4/47) were unspecified road users, and there was one group of motorcyclists and cyclists. Our findings confirmed that MMPU is related to risky behaviour on the roads. In the 29 studies considering observed or self-reported behaviour, 90.9% (30/33) found that road users who scored higher in MMPU are more likely to use their phones on the road as cyclists, drivers, motorcyclists, and pedestrians. Of the nine studies that analysed performance changes, 55.6% (5/9) showed evidence that MMPU changes the performance of road users engaging in mobile phone use, meaning that there is evidence suggesting that MMPU determines the level of impairment. Of the nine studies that analysed the safety-related-outcomes, 66.7% (6/9) found that the higher the MMPU score, the more likely road users are to experience safety–critical traffic events. This review contributes to the literature by showing a pathway between the negative health consequences of MMPU and road trauma. We also identified that the quality of the studies was generally low due to study design and blinding aspects. This field of research also lacks standard practices as researchers avoid using established and well-validated questionnaires, often creating new ones to measure MMPU. This hinders the generalisability of the findings and raises questions about the construct validity and external validity of MMPU. The usefulness of future research would be enhanced by a consistent methodological approach using the same scales based on standard behavioural definitions. The cross-disciplinary nature of MMPU effects means that transport and road safety professionals need to work with healthcare professionals and technology organisations to understand and address MMPU as a contributing factor to road crashes.