Can the difficulty level reached in computer-based training predict results in x-ray image interpretation tests?

As scientific studies have shown, the performance of airport security screening officers in x-ray image interpretation depends critically on individual abilities and visual knowledge acquired through class-room, computer-based (CBT) and on-the job training. The effectiveness of adaptive CBT in increasing the efficiency in x-ray image interpretation of screening officers could be verified in several studies. Individually adaptive CBT systems, like X-Ray Tutor (XRT), are constructed in such a way that with increasing performance of each individual the difficulty level will increase and become more challenging with respect to three imaged-based factors: viewpoint (depending on rotation of threat items in a bag), superposition by other items and bag complexity. The focus of this study was to examine to what extend the achieved training level in XRT positively correlates with performance in the X-Ray Competency Assessment Test (X-Ray CAT) or, more specifically, whether screeners that have acquired higher difficulty levels also achieved better test results. Knowledge about an acquired difficulty level could then, subsequently, provide an indication about the screeners' x-ray image interpretation competency. Furthermore, analysis of these correlations would suggest which XRT difficulty level screening officers should have mastered in order to be acknowledged as proficient, and for them to be well prepared to pass initial and recurrent certification with the X-Ray CAT. The latter is of particular interest as the X-Ray CAT is being used for certification at several European airports. A further goal of this study was to reproduce results of previous studies confirming the effectiveness of adaptive CBT for increasing detection performance of screeners. The study was carried out at one international airport. 199 screening officers underwent training with XRT for 20 months. Assessments were taken before the start, after 13 months and finally after 20 months of training. Analyses showed high positive correlations between the achieved XRT training levels and the individual's performance in the X-Ray CAT. Based on these results, recommendations on which XRT level should be reached before initial and recurrent certification of x-ray image interpretation competency are derived. Furthermore, large increases in detection performance were found when comparing performance obtained at the three measurement dates, supporting results of earlier studies.