In the past, gamification studies revealed that one-size-fits all solutions are not sufficient for successfully addressing every human being. Thus, empirical investigations are necessary, examining inter-personal varying effects of gamification that is adapted to the users. The proposed experimental design describes the investigation of moderating personality influences on gamification outcomes, i.e. energy saving task performance. Therefore, we conduct a laboratory experiment in the context of sustainable behavior. Behavioral Inhibition System and Behavioral Activation System, two distinct neuropsychological motivational systems based on the Reinforcement Sensitivity Theory, are described as promising predictors for inter-personal varying outcomes of gamification. Participants have to face a dual task condition, in which an avatar is realized as a game design element and expected to cause an attentional shift concerning task priorities. Our proposed study will contribute to gamification research and practice by providing knowledge allowing the inter-personal adaption of game design elements in a subsequent step.