X-ray screening of passenger bags is an essential task at airport security checkpoints. In this study we investigated how well airport security screeners can detect guns, knives, improvised explosive devices (IEDs) and other threat objects in X-ray images of passenger bags before and after 3 and 6 months of recurrent (about 20 min per week) computer-based training (CBT). Two experiments conducted at different airports gave very similar results. Training with X-ray Tutor (XRT), an individually adaptive CBT, resulted in large performance increases, especially for detecting IEDs. While performance for detecting IEDs was initially substantially lower than for guns, IEDs could be detected as well as guns after several months of training. A large transfer effect was observed as well: Training with XRT helped screeners recognize new threat objects that were similar in shape as the trained objects. Threat recognition was dependent on the rotation of the objects. If depicted from an unusual viewpoint, prohibited items were more difficult to recognize. The results were compared to two conventional (not adaptive) CBT systems. For one system no training and transfer effects were observed whereas small training and transfer effects were found for the other conventional CBT system.

A central aspect of airport security is reliable detection of forbidden objects in passenger bags using X-ray screening equipment. Human recognition involves visual processing of the X-ray image and matching items with object representations stored in visual memory. Thus, without knowing which objects are forbidden and what they look like, prohibited items are difficult to recognize (aspect of visual knowledge). In order to measure whether a screener has acquired the necessary visual knowledge, we have applied the prohibited items test (PIT). This test contains different forbidden items according to international prohibited items lists. The items are placed in X-ray images of passenger bags so that the object shapes can be seen relatively well. Since all images can be inspected for 10 seconds, failing to recognize a threat item can be mainly attributed to a lack of visual knowledge. The object recognition test (ORT) is more related to visual processing and encoding. Three image-based factors can be distinguished that challenge different visual processing abilities. First, depending on the rotation within a bag, an object can be more or less difficult to recognize (effect of viewpoint). Second, prohibited items can be more or less superimposed by other objects, which can impair detection performance (effect of superposition). Third, the number and type of other objects in a bag can challenge visual search and processing capacity (effect of bag complexity). The ORT has been developed to measure how well screeners can cope with these image-based factors. This test contains only guns and knives, placed into bags in different views with different superposition and complexity levels. Detection performance is determined by the ability of a screener to detect threat items despite rotation, superposition and bag complexity. Since the shapes of guns and knives are usually known well even by novices, the aspect of visual threat object knowledge is of minor importance in this test. Abstract -A central aspect of airport security is reliable detection of forbidden objects in passenger bags using Xray screening equipment. Human recognition involves visual processing of the X-ray image and matching items with object representations stored in visual memory. Thus, without knowing which objects are forbidden and what they look like, prohibited items are difficult to recognize (aspect of visual knowledge). In order to measure whether a screener has acquired the necessary visual knowledge, we have applied the prohibited items test (PIT). This test contains different forbidden items according to international prohibited items lists. The items are placed in X-ray images of passenger bags so that the object shapes can be seen relatively well. Since all images can he inspected for 10 seconds, failing to recognize a threat item can be mainly attributed to a lack of visual knowledge.The object recognition test (ORT) is more related to visual processing and encoding. Three image-based factors can be distinguished that challenge d...

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In recent years, research on cognitive aging increasingly has focused on the cognitive development across middle adulthood. However, little is still known about the long-term effects of intensive job-specific training of fluid intellectual abilities. In this study we examined the effects of age- and job-specific practice of cognitive abilities on detection performance in airport security x-ray screening. In Experiment 1 (N = 308; 24–65 years), we examined performance in the X-ray Object Recognition Test (ORT), a speeded visual object recognition task in which participants have to find dangerous items in x-ray images of passenger bags; and in Experiment 2 (N = 155; 20–61 years) in an on-the-job object recognition test frequently used in baggage screening. Results from both experiments show high performance in older adults and significant negative age correlations that cannot be overcome by more years of job-specific experience. We discuss the implications of our findings for theories of lifespan cognitive development and training concepts.

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