Esther Mertens

| 47 Effectiveness of a Psychophysical Intervention The second aimwas to examine if intervention effectswere influencedby thewidthof the intervention’s ecological focus, i.e., the extent towhichmultiple systems are involved in the intervention. As stated in the social ecological model of Bronfenbrenner (1979), behavior is determined by the interactions of multiple systems such as the individual, family, and school systems. Whenmore systems are actively involved in an intervention, students are more exposed to the intervention which could increase its effectiveness. For instance, Flay, Graumlich, Segawa, Burns, and Holliday (2004) examined the influence of involving multiple systems on the effectiveness of a social-emotional intervention aiming to reduce risk behaviors. They found stronger intervention effects when the intervention was not only implemented in the classroom, but also in the whole school and when parents were involved. However, this positive effect of a broad ecological focus of interventions is not always found. For instance, Durlak and colleagues (2011) found in their meta-analysis that interventions that involved the whole school and/or parents were not more effective than interventions that were only implemented in the classroom. These inconsistent findings indicate that more research is needed to clarify the influence of the width of an intervention’s ecological focus on intervention effects. This knowledge is pivotal for schools in order to determine the extent of investment in intervention (e.g., number of teachers to train, whether or not to involve parents) that is necessary for intervention to work. In sum, the present study had two aims. First, we examined whether a universal school-based intervention, R&W, could stimulate prevocational students’ development in the intrapersonal and interpersonal domains. We hypothesized that R&Wwould be more effective than care as usual due to its unique approach that matches the learning processes of this group of students. Second, we examined the influence of the width of the ecological focus on intervention effects. We had no specific hypothesis concerning this aim, as research on the influence of ecological focus on the effectiveness of interventions is inconsistent. Method Design and Procedure The effectiveness of R&W was examined in a Randomized Controlled Trial with four conditions that differ in width of the ecological focus. In the ‘Light’ condition only a core team of teachers was involved in the intervention. In the ‘Standard’ condition the entire teaching staff was involved. In the ‘Plus’ condition the entire teaching staff as well as parents were involved. In the Control condition, schools conducted their current school policy to enhance students’ competencies and prevent problems in the intra- and interpersonal domain (i.e., care as usual). 3