In this project, we perform a user study to evaluate the effectiveness of Social Choice-Based Explanations for Group Recommender Systems using internal evaluators (i.e., group members evaluate the recommendations provided for the group), in different complex scenarios, whose complexity is determined by the number of group members, the number of possible items, and the diversity between group members' preferences. For additional details and material refer to the OSF project: https://osf.io/sj76m/