https://www.researchgate.net/publication/3278148_Aviation_security_screeners_Visual_abilities_visual_knowledge_measurement (Any fulltext)
Schwaninger, A., Hardmeier, D., & Hofer, F. (2005). Aviation security screeners visual abilities visual knowledge measurement. IEEE Aerospace and Electronic Systems Magazine, 20(6), 29-35. doi:10.1109/MAES.2005.1412124.