Detection of terrorist threats in air passenger luggage: expertise development

Currently, detecting potential threats in air passenger baggage heavily depends on the human examination of X-ray images of individual luggage items. In order to improve the performance of airport security personnel in searching images of air passenger luggage it is important first to understand fully the requirements of the demanding task. Here, an experiment is reported where eye movements of naive observers and screeners were recorded when they searched 30 X-ray images of air passenger luggage for potential terrorist threat items such as guns, knives and improvised explosive devices. Compared with novices, the advantages of the screeners were speed and accuracy in detecting threats. Eye position data revealed that screeners were faster to fixate on target areas and once they fixated on targets their hit rate was significantly higher. Most of the IEDs were missed by both naive observers and screeners due to interpretation errors which indicated the importance of training. Stimulus salience at the first fixation locations of naive observers and screeners was compared to investigate expertise development. It was found that experience did not change attention preference on stimuli properties at the beginning of the observers visual search. The implications and further studies are discussed.