Ethics approval
This study was approved by the institutional review board of the ethics committee. Written informed consent was secured from all of the subjects. The authors assert that all of the procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. This study protocol was approved by the Ethics Committee of the Faculty of Psychology at the Ruhr University Bochum, approval number: 036.