First research findings suggest that the influence of digital media on children's and adolescents' health depends primarily on proper use and regulation. In line with Social Cognitive Theory, parents' own mobile device use is very important to regulate children's media use because parents are their children's role models. However, parents do not always behave as optimal role models: They use smartphones on playgrounds, in restaurants, as well as during family mealtimes. This usage of mobile devices leads to interruptions during face-to-face conversations or routines which is defined as "technoference". Studies among children and parents suggest that parental mobile device use is associated with fewer parent-child interactions. In addition, first studies investigated mobile device use at the dining table and showed that mothers had less interactions with their children during meal times when they used a mobile device compared to mothers who did not and their children were also less likely to try new and unfamiliar food. Along the same lines, lower parental mobile device use during mealtime is also associated with healthier body weight in children. AIM: Examination of the effect of a time out from smartphone use during a family meal on the parent-child interaction at the meal table and eating quality in comparison to family meals where participants use the smartphone as usual. DESIGN: The study is a within-family field experiment with daily assessments over 14 days (7 days for the experimental condition, 7 days for the control condition). Families will go through both, intervention and control condition with a break of 21 days in between. The assessment of the main and secondary outcomes is conducted at the baseline, over a 14 day daily diary phase and at the follow-up (directly after the daily diary phase). The sample will consist of 120 families with at least one child between the age of 6 to 14 years old. Only the participating adult in the study fills in the questionnaires. OUTCOMES: (Un)healthy eating and parent-child interaction constitute the main outcome, whereas technoference, mealtime duration, atmosphere at the meal table, and smartphone use frequency are secondary outcomes.

Emerging mobile and digital technologies such as smartphones, tablets, wearables, and other mobile devices are an integral part in the daily lives of children, adolescents, and their families. The intensive use of mobile devices has both, positive aspects and negative side effects: The main advantages include access to information and making it easy to maintain social relationships. Potentially harmful risks for children include delays in small children's speech development, concentration disorders in primary school aged children or an increased consumption of sweet drinks and sweets. Especially parental media supervision is needed to regulate children's media use. In line with Social Cognitive Theory, parents' own mobile device use is also very important to regulate children's media use because parents are their children's role models. However, parents do not always behave as optimal role models: They use smartphones on playgrounds, as well as during family mealtimes. This usage of mobile devices leads to interruptions during face-to-face conversations or routines which is defined as "technoference". Studies among children and parents suggest that parental mobile device use is associated with fewer parent-child interactions. Especially using smartphones during shared meals could negatively influence interactions at the dining table as well as healthy eating habits in children. First findings suggest that the use of smartphones during family meals has detrimental effects on the family meal itself (e.g., interactions) as well as the health of the family members (e.g., diet quality and body weight). Importantly, these studies are all observational or cross-sectional, thus, experimental research is needed to understand whether taking the smartphone away from the family meal will actually lead to better interactions and healthier meals. While some experts suggest to ban smartphones from the dinner table, no one has systematically tested the effects. Thus, the aim of the proposed study is to experimentally test the effects of using smartphones at family meals versus banning them from the meal table and to examine potential mechanisms underlying this relation.

Inclusion Criteria:

• One parent who 1. lives in a household with at least one child aged between 6 and 14 years 2. eats a family meal (shared meal) with this child at least 5 days/week 3. owns an Android smartphone 4. has mobile internet on the smartphone 5. uses the smartphone on a daily basis 6. uses the smartphone at least sometimes during shared meals 5. agrees on participating in the study.

Exclusion Criteria:

1. Insufficient knowledge of German of the participating family member
2. Involvement of the participating family member and/or child in a dietary program to reduce weight or plan to do so for the duration of the study.
3. Holidays during the intervention period

We plan to provide the anonymized data set and the coding scheme.

Families are assigned to the 2 conditions in a random order without knowing the aim of the intervention.