Received: 13 May 2019
Accepted: 20 February 2020
First Online: 4 March 2020
Ethics approval and consent to participate
: All subjects provided their written informed consent to their voluntary participation in this study and for the publication of their data. The study has been approved by the local ethics committee of Faculty of Social and Behavioural Sciences, Friedrich Schiller University Jena (protocol number: FSV 16/13) and followed the principles of the Helsinki Declaration.
: Not applicable.
: None. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.