We thank Aysan Amirghiyasvand, Miriam Delgado, Jan Philipp Kehr-Ritz, Gloria Lew, Neele Penning, Baheschtae Said, Nora Kimberly Scholz and Thore Würger for their help with data collection. We also thank Helfer HBF e.V. and Majd Awad for their support with the acquisition of participants. The manuscript was written during the lifetime of Franz Petermann, who was substantially involved in the implementation and conception of the work.