Persona Development for Child–Parent Co-Design in Reducing Children’s Consumption of Energy-Dense Snacks

Co-design is widely used to address social problems by fostering shared understanding and collaboration. However, in family behavior contexts such as children’s eating habits, research integrating child–parent interactions remains limited. In addition, the transtheoretical model (TTM), commonly used in behavior change studies, focuses mainly on individual change and insufficiently reflects relational dynamics. This study develops child–parent personas by integrating behavior change stages with co-design processes in the context of reducing children’s consumption of energy-dense snacks. Semi-structured interviews were conducted with thirty parents of children aged 6–12 years. The data were analyzed across TTM stages—pre-contemplation, contemplation, preparation, action, and maintenance—focusing on children’s snack consumption behaviors, parental responses, and interaction patterns. Cross-stage patterns were examined and reorganized based on the degree of relational alignment, forming the basis for persona development. The findings show that behavior change stages differ by the level of alignment between parents and children: low in early stages, partial in preparation, and high in later stages. These patterns were reconfigured into three clusters and developed into three persona types: Empathy-Based Exploratory, Incremental Action, and Sustained Action. The study also finds that co-design facilitates shared understanding and communication, while posing challenges such as parental burden and difficulty engaging children. By framing behavior change as a process of relational alignment, this study offers both theoretical and practical contributions.