Recruitment of underage test persons: motivators and barriers in an anthropological EU-survey on a sensitive topic.

Recruiting test persons is crucial in many scientific fields. The recognition of motivators or barriers to survey participation may support the design and recruitment strategy of future studies. The recruitment of under age test persons is very complex and sensitive. This paperpresents and analyses the experiences in recruitment of female juveniles (10-18 years old) in Germany, Italy and Lithuania within the context of an EU funded project concerning the extremely sensitive topic of "child pornography". The purpose of the project was to develop a method for age estimation of juveniles on photographs and videos. The faces of the test persons were photographed and anthropologically measured after an informed consent was signed by their parents and themselves. The analysis of the recruitment strategies and response rates revealed that culturally influenced factors played a significant role in the individual decision for or against a participation in the study. In all countries, the sensitive topic of child pornography had a great influence on the decision process. Many German parents agreed especially in light of this topic while in Italy and Lithuania the word "child pornography" triggered a very negative response. In Germany, the anthropological investigation of the faces provoked negative associations with the anthropometric surveys in the Third Reich. Social and political climate were further relevant factors for decision-making especially in Lithuania. The "top-down" principle of recruitment proved to be very effective for this kind of study. The authorities of headmasters, scientists and institutions positively influenced the decisions of the parents.