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Measuring visual abilities and visual knowledge of aviation security screeners


Schwaninger, Adrian; Hardmeier, Diana; Hofer, Franziska (2004). Measuring visual abilities and visual knowledge of aviation security screeners. In: Proceedings of the 38th Carnahan Conference on Security Technology, Albuquerque, NM, 11 October 2004 - 14 October 2004, 258-264.

Abstract

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 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.

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Additional indexing

Item Type:Conference or Workshop Item (Paper), refereed, further contribution
Communities & Collections:06 Faculty of Arts > Institute of Psychology
Dewey Decimal Classification:150 Psychology
Language:English
Event End Date:14 October 2004
Deposited On:13 Aug 2014 10:57
Last Modified:19 Jul 2018 07:25
Publisher:O E S Publications
Series Name:International Carnahan Conference of Security Technology. Proceedings
ISSN:1071-6572
ISBN:0-7803-8506-3
OA Status:Green
Publisher DOI:https://doi.org/10.1109/CCST.2004.1405402

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